Heartstopper · S2 E8Sleuthed by @shelfsleuth
Heartstopper · S2 E8 · Isaac Henderson · Decorating the school for prom
Isaac decorating for prom: Summer Bird Blue
Akemi Dawn Bowman's 2018 novel about Rumi Seto, who moves to Hawaii after her sister dies and starts to work out that she doesn't feel attraction the way people expect. The writers put the season finale's twist in his hand and nobody in the gym noticed.
Sources: All the books Isaac reads in Heartstopper, season two, Meeghan reads · Every book that Isaac reads in Heartstopper, Kobo · Every Book Isaac Reads in Heartstopper Season 2, Den of Geek · All of the books Isaac reads in Heartstopper season two, PinkNews · A Complete Heartstopper Book List, The Geeky Waffle