Shuugakuryokou de Nakayokunai Group ni Hairimashita

Ordinary high schooler Hioki is feeling low after he's placed into a class with none of his friends. Just as he's about to be alone for the school trip, he's dragged into the group with the super cool and popular Watarai. Hiroki is initially nervous around him, but his anxiety fades as Watarai always stays by his side, looking out for him. As they slowly open up to each other, Watarai's deep obsessiveness begins to show...

(Source: Starts Publishing, translated)