Shinjou Kokyuu  

Heartbeat, again, 心情呼吸, 심정호흡

A biology teacher named Nara was admitted by a student named Ikuta for having broken his heart in the past. Despite this, Nara avoids interacting with Ikuta due to the emotional pain he experienced before. However, after much persistence from Ikuta, Nara agrees to reciprocate his feelings towards him. On one condition, though: what could that be?