Hamtaro, the curious pet hamster of 5th grader Laura Haruna, sets out to meet the neighbors after they move to a new town. While Laura enjoys a snack with her parents, Hamtaro sneaks out of his cage and down the drainpipe. Once outside, he meets his hamster neighbor Oxnard, who is looking for his missing sunflower seed. Hamtaro helps him find it and they declare each other friends afterwards.

On Laura’s first day of school, Hamtaro can't help Laura choose the perfect outfit, but he decides to help by keeping an eye on her at school. He soon gets sidetracked though when he runs into his new friends Oxnard and Boss, who introduce him to more hamster pals, Pashmina, Penelope, Howdy and Dexter.

Since the opening of the Ham-Ham Clubhouse, Hamtaro is meeting new hamsters every day. Pashmina and Penelope introduce their friends Maxwell, Panda and Sandy. Cappy also sneaks up on them under a saucepan, and they become friends. But with all the new Hamsters come Ham-personalities that clash. One day when this happens, a fed-up Boss kicks everyone out the clubhouse.

Boss is cleaning the Clubhouse to invite Bijou over. He, Hamtaro, and Oxnard go visit Bijou to persuade her to come. She refuses, because she has never been outside of her cage, and her owner would be worried when she finds out she's gone.

One day, while listening to Laura and Kana plan an evening barbecue, Hamtaro becomes enchanted by what the girls are eating--a sparkling candy called “Diamonds of Sugar”. Puzzled, Hamtaro goes to the Ham-Ham Clubhouse to ask his friends if they’ve heard of these "diamond things". After many theories from the hamsters, Boss insists the candies come from the sky and are best seen at night.

Laura's parents take her on her first trip to the beach; but when they tell her that the water can be dangerous for hamsters, she decides not to take Hamtaro. However, Hamtaro and the Ham-Hams have other ideas! They want to see the ocean, so they make a plan to go to the beach too, after agreeing that if they stick together, they can look out for one another.

It's a summer festival! The Ham-Hams learn from Maxwell that on the night of the festival, flowers (fireworks) will appear in the sky. Pashmina separates from the Ham-Hams to find the flowers.

Hamtaro goes with Laura and her family to visit her grandmother in the country. The Ham-Hams are excited for Hamtaro, because Grandmother's house is surrounded by sunflower fields.

After Laura begins a new semester, the Ham-Ham pals start to wonder if they might be missing something by not going to school. After Hamtaro, Oxnard, and Boss sneak into Laura's school for a day to check things out, the Ham-Hams set up a separate school of their own.

Laura's father asks her to deliver an important floppy disk to his office. While Laura packs her bag, Hamtaro gets trapped inside. On the way to Mr. Haruna's office, Hamtaro picks up two hitchhikers, Oxnard and Penelope, who have just escaped from an angry crow. When Oxnard's sunflower seed falls to the ground, Oxnard jumps out of Laura's bag to go after it, and Hamtaro and baby Penelope follow, not knowing that the yellow disk has slipped out of Laura's bag too.

It's Grandparents Day, and when Grandma comes for a visit she shows Laura an old clock that she and her friend, Kaitlyn, bought years ago. Laura is touched by the story and decides to surprise her grandmother by trying to find her long-lost friend for her.

When Laura and Kana go shopping, the Ham-Hams go along, but soon find danger in the shopping district. Bijou wanders down a nearby alley, but she doesn't return!

As Elder Ham's Sunflower Seed Harvest Festival approaches, Sandy confesses to Hamtaro that she has a crush on Maxwell because he reminds him of her brother. Sandy asks Hamtaro to find out if Maxwell feels the same about her.

Picking up where the last episode left off, Hamtaro and Oxnard locate Sandy's twin brother, Stan, and bring him back to the Clubhouse. To celebrate, the Ham-Ham gang decides to throw a surprise reunion party for Sandy.

In a game of Blind Man's Bluff, Cappy takes Bijou's ribbon on accident, but Hamtaro gets the blame. To make it up to her, everyone plans a trip to Acorn Mountain and collects some acorns to help her feel better.

Laura's gone down with a cold, and Hamtaro feels terrible about her condition because he kept running on his wheel all night. Meanwhile, Boss develops a "stomach-ache" and Maxwell steps in to help cure him with yogurt found in Laura's fridge.

All of the Ham-Ham's special items have suddenly gone missing! Luckily, Hamtaro is on the case and wants to know what's going on and who really had an intent on stealing everyone's things.

When Laura is asked to perform the role of Cinderella in the school play, the nervous actress accidentally leaves one glass slipper at home. When Hamtaro discovers the lost slipper, he and his Ham-Ham friends set out to secretly deliver the slipper to the theater.

Despite Boss, Howdy and Stan's stubbornness, the Ham-Hams decide to build a fun park under Panda's leadership. Meanwhile, Laura's family goes to the amusement park, but the car machinery breaks down.

During spring-cleaning at the Clubhouse, the Ham-Hams can’t wake up Snoozer, so they haul him outside on a table and leave him with the rest of the furniture. Then a remote-control car, powered by two boys, crashes into the desk and carries him away. In the meantime, Snoozer’s drowsy personality sparks some discussion among the Ham-Hams who realize that they don’t really know who their sleepy friend is.

Admiring his courageous and heroic background, Cappy decides that he wants to become a field hamster just like Boss, and the Ham-Hams are worried about him losing his home life with his owners, Kip and Sue.

Today is Travis' birthday, but Laura's having a hard time finding the perfect gift to give for him on that special day. Hamtaro, with the same idea in mind, declares a competition with Pashmina as the judge to see who can give her the best gift.

Maxwell decides to create a newspaper called "The Ham-Ham Times" after Hamtaro learns that Laura and Kana are making a newspaper for the school. The Ham-Hams set out to each find news worthy of the paper.

While on a walk with Laura, Hamtaro falls into a box on a transport truck in an attempt to save one of Laura's ribbons and is taken away. Laura becomes very distraught. The Ham-Hams become determined to start searching for Hamtaro.

It's Christmas time! Boss and Snoozer want to get a gift from Santa. The Ham-Hams decide to help and everyone gets gifts from the hamster-Santa. Meanwhile, Laura wants a dollhouse for her gift.

Hamtaro and Laura dream about being a princess and a knight in a fairy tale. The prophet hamster (Elder Ham) foretells the arrival of an evil magician and a brave knight. The brave knight (Hamtaro) arrives. Can he save the kingdom?

With snow laden on the ground, the Ham-Hams decide to go out and play... but Boss and Stan get into a quarrel over who is the best at snow sports! Who will win the Ham-on-ice Challenge? Boss or Stan?

There is a marathon race at Laura’s school and a friend of Elder Ham’s, the eccentric Auntie Viv, comes to town to participate. When the race begins, Auntie Viv and an equally competitive Boss charge out of the starting gate.

After Laura’s father looses his favorite pair of eyeglasses, he, Laura and Hamtaro go off to the optical shop for some new ones. After trying on several pairs, a frustrated Mr. Haruna decides to keep looking for his old one’s.

Hamtaro and the family dog Brandy go with Laura to a dog-sled race. Brandy, who only gets exercise from yawning and walking in and out of his doghouse, just goes to watch; but he begins to worry about embarrassing Laura with his laziness, so he decides to sign up for the race.

Boss, the self-appointed chief of the Ham-Ham Clubhouse is acting strange lately, and the other Ham-Hams are concerned. They decide to follow him one day and soon discover that he’s caring for an abandoned kitten.

It is Valentine’s Day, and Laura decides to make chocolates for Travis. In the Ham-Ham Clubhouse, the traveling Auntie Viv appears, wanting to give a Valentine gift to Elder Ham. The girl hamsters are thrilled at her romantic gesture and encourage the boy hamsters to help Auntie Viv find Elder Ham.

At the Ham-Ham Clubhouse,the Ham Hams see a rainbow. Some of them think they can nibble on it. Bijou arrives after the rainbow disappears and she and the Ham Hams think she will "lose her colors" now. Boss tries to find a rainbow for her but is unable to.

Pashmina is going out for the day without Penelope, so in an attempt to impress Pashmina, Dexter and Howdy volunteer to baby-sit so Penelope won’t be alone. Howdy and Dexter, both competing to be the best babysitter end up fighting with each other and a neglected Penelope wanders away.

It’s almost Mimi's birthday and the girls celebrate with Chinese Doll displays and treats. As the Hamsters are trying to understand the holiday, they find themselves following Mimi down the street, because they see her carrying the food they love, Rice Crackers.

When Maria's parents decide to go back to France so she can study piano, Bijou must bid her Ham-Ham friends goodbye. She finds it hard to tell them and when she finally does, the hamsters are in shock.

Kana’s cousin, Dylan lives on a farm called the Flower Ranch with his parents and pet hamster, Pepper. One day Kana and Laura and their families visit them and bring Hamtaro and Oxnard along. On the way, Oxnard tells Hamtaro about the huge crush he has on Pepper and hearing this, his good friend Hamtaro encourages him to tell her about his feelings that day.

When Mr. Haruna plans to go on a business trip to their old town, Laura wants to go along, hoping to hook-up with her old friend Melanie. After Laura fails to reach Melanie by phone, she decides to send a letter. But Laura never gets a reply so a curious Hamtaro takes it up at the Clubhouse and says he wants to investigate. Just then Jingle appears and Boss and the seasoned globetrotter agree to solve the mystery.

Hamtaro wants to learn to fly after Jingle relays the “Tale of the Flying Hamster.” Then they find a scroll about this special hamster in Panda’s house and his determination increases. In the meantime, Laura is trying to decide on a flower design for a school project and goes to the park, allowing Hamtaro time to persuade his Ham-Ham pals to join his new adventure.

Hamtaro, hearing Laura and Kana talking about going on a picnic, thinks that it would be a great idea for the ham-hams as well. He takes the idea to the ham-ham gang. Everyone thinks it's great, except for Penelope and Bijou, who don't know what a picnic is and wonder what involves.

Laura visits the local museum to gain some information for an independent study assignment. As she talks with her family about it, they talk about something at the museum that they think looks like a giant sunflower seed. Hamtaro, listening in, focuses on ""giant sunflower seed."" He takes the news to the ham-ham gang, who wonder about the origin of this giant sunflower seed. They think maybe that aliens brought it to the planet Earth. One thing they do know: they have to get the museum to check this out.

Kana's country cousin, Dylan is coming for a visit and he's bringing his hamster, Penelope, with him. Oxnard is still madly in love with Pepper and can't wait for her to come. Meanwhile, all of the ham-hams are planning a surprise party to welcome Pepper.

When Laura and the other students study zoology in Mr. Yoshi’s class, everyone brings their pets. While the animals play on the counters and in the strange science sinks, Oxnard strays off to look for food. He finds some corn and starts eating it, but then realizes he’s in the cage of the mean Chicken Trio: Gonzales, Vinny and Capone.

On Children’s Day, Laura’s Grandpa comes to visit, bringing with him his latest invention, a fully automated treadwheel. He decides to test it on Hamtaro and before long, the wheel throws Hamtaro across the room. Laura gets upset with her grandfather and leaves the house.

Laura and Kana visit the Aquarium with their fathers, and the Ham-Hams follow along. Inside the Aquarium, strange sea creatures overwhelm the hamsters, but Hamtaro recognizes it as the place from the fairy tale that Laura read the night before.

There is a Sports Festival at Laura and Kana’s school, and the girls are participating in the Parent-Child Triathlon with their fathers. The Ham-Ham’s decide that they want to organize a competition of their own, so they attend the festival to see what’s involved.

Mr. Yoshi, Laura’s teacher, cannot forget Charlotte, the beautiful woman he met in the wild classroom chicken incident, so the Ham-Ham girls (who are natural romantics) set out to find her.

During the rainy season, the Ham-Ham’s want a change of atmosphere so they decide to redecorate the Clubhouse. After they finish, they try to go outside, but find that the door won’t budge, because a mole dug a hole while they were decorating. The mole-hole has brought mud & water into their tunnel, and it threatens to seep into the Clubhouse!

After Laura's parents have an argument, Dad leaves the house with Laura. As a worried Hamtaro watches them go, the Ham-poet Jingle appears. In the meantime, Laura and her dad go to the department store and buy her mom a pretty pendant for Laura’s parent’s anniversary, but when they get home, Laura discovers the pendant is missing.

Laura’s social studies class takes a field trip to the harbor to ride a sightseeing boat. Boss claims to be an expert on boats and harbors, so the hamsters follow along. When they get there, however, they soon realize that Boss has never been near a boat or a harbor in his whole hamster life.