Kodomo no Omocha
Genres: Comedy, Drama
Type: OVA, Episodes: 1
Aired: Dec 16, 1995
Studio: J.C.Staff
Source: Manga
Rating: PG - Children
Synopsis:
The Kodomo No Omocha OVA is a thirty-minute animation video that was made before the TV series. It covers the first volume of the manga, so it's equivalent to TV episodes 1-6. It relates Sana's troubles with Hayama at school as a result of the "oyakodon baka" situation and culminates when Hayama's dad and sister realize their mistakes thanks to Sana's efforts. 

(Source: AniDB)