Tottoko Hamtarou: Anime Dechu!
Genres: Adventure
Type: OVA, Episodes: 1
Aired: Sep 15, 1999
Source: Manga
Rating: G - All Ages
Synopsis:
This was the first attempt at an animated adaptation of Hamtarou, and consists of four short episodes. 

Crawling Around, Hamtarou (ドラマ ~ もぐりこんだら ハム太郎): Natsumi comes home and finds Hamtarou is missing from his cage. Shortly after, Hamtarou is revealed to be hiding under Natsumi's blanket, where he introduces himself to the viewer.

Hamuchanzu Corner ~ Biscuits in the Vase (ハムちゃんずコーナー ~ つぼの中のビスケット): Hamtarou and the Ham-Hams help Bijou retrieve a biscuit she had dropped while running on the roof posts. After multiple attempts to retrieve the cookie fail, Hamtarou suggests that he be lowered down into the vase, like a prize-catching crane machine. With this plan, Hamtarou is able to retrieve Bijou's biscuit. The vase wobbles and he begins to fall, but the dog wakes up and rescues the hamster by catching him with a pillow. With Hamtarou saved, Bijou hugs Hamtarou graciously and the episode ends as Hamtarou watches the dog slip away to go back to sleep.

I Love You, Natsumi-chan (ドラマ ~ 大好き、なつみちゃん): The episode opens with Hamtarou having a bit of a manly montage; he seems like he has something important to do. Before she leaves for school, Natsumi tells Hamtarou she likes him while petting him. In response, without her understanding, Hamtarou confesses to Natsumi that he loves her romantically, but knows that Natsumi only loves him as a companion. She then has to leave for school and meets her classmate, Shirohara, to walk with him. Hamtarou wishes to become rivals with the schoolboy, who he knows Natsumi has a crush on. He spends the day venting and whining to Wanta about how Shirohara has beaten him for Natsumi's affection, and eventually tires himself out. At the end of the day, however, Natsumi tells Hamtarou that she loves him very much, which makes him very happy.

Hamuchanzu Corner ~ Yellow Happiness (ハムちゃんずコーナー ~ 黄色いしあわせ): Hamtarou and the Ham-Hams appear to be on a scheme to get some sunflower seeds.

(Source: Wikia)