Who's Oikawa Ayumi?!.Mikako's nightmare of Tsutomu abruptly confessing his feelings for her becoming the preamble for Mikako lashing out at Tsutomu's sneak peek offer during the commute to school hinders the moment of male bonding between Shintaro and Yuusuke as a result of Mariko failing to cover all her bases. While Yuusuke reflects upon his past with Mariko whose apology for the earlier misunderstanding prompts him to race off with Jiro in hot pursuit, Tsutomu's introduction of his classmate Ayumi Oikawa sets Mikako to wondering what kind of collaborative past they share...