There were two animeOVA adaptations of the game, a two-episode hentai OVA in 2002, and Mizuiro 2003, a two-episode non-hentai OVA in 2003. Both have same characters, but with somewhat different storylines.
Prologue: The player's character is very young, with the story beginning with the meeting of Yuki for the first time and developing a loving sibling relationship although they are not both related in blood as Yuki was adopted.
Pre-Opening: The player makes choices to decide the story of the game, with the players character still very young. The first meeting of Hiyori occurs, who is a lost girl crying in the park. The game then presents the problems of the character that your choices led to.
Game: The players character is in the second year of senior high in the game (grade 11). A story about a character is presented to the player depending on the choices made in the last setting. Each story has a moving or tragic situation.
Voice: Most of the female characters you encounter have a very calm voice, though it depends on the situation.