Yotsunoha
Genres: Romance
Type: OVA, Episodes: 2
Aired: Feb 29, 2008 to Mar 28, 2008
Studio: Hal Film Maker
Source: Visual novel
Rating: PG-13 - Teens 13 or older
Synopsis:
Based on the game by Haikuo-Soft.

A story about the reunion of 4 childhood friends, Yuzuki, Matsuri, Nono and Makoto, in their deserted old school campus, Mochitsuki Academy. 3 years ago, they buried a time capsule under a tree inside the school and made a promise. A promise to meet again after exactly 3 years from that day. And the day of promise has finally arrived.

(Source: AniDB)