Episode 4 (S01E04)

While Shiro heads out for a butterfly observation survey, Itaru remains at home, captivated by his father's collection of specimens. He decides to invite some friends over and begins documenting his own observations in a report. Upon Shiro's return, they enjoy dinner together, reminiscing about old times. Shiro feels a peculiar connection as he accesses Itaru's computer, glancing at the specimens in the room. Fast forward three years, and Shiro receives a letter from Anna, stirring up memories from the past.