@AthalosJ that's not his sister, that's his aunt, and she's overprotective as fuck because she pushed him to go meet the gyaru and feels responsible that he almost died for it
And yes @kronix is right, his aunt wants his D because of the guilt more than anything, also I'm glad you liked the trap
with all the traps in these harem mangas lately, it’d be just a matter of time until there’s one where the MC just ditches all the other girls and go for the trap instead