Responses
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a good example of "u don't need kids involved to achieve your story's purpose" is https://www.mangago.zone/read-manga/kamikudaite_aio_oshiete/
literally on the same urges, self control, guilt felt by the character because he cannot control himself.
This is actually insane. The author HAS CHOSEN to write a kid who's jerking off at the thought of another kid who's 10 YEARS YOUNGER because of FATE? no babes, that's the author's choice, she deliberately chose to make the most pedophilic baiting story about an adolescent and a little kid. There's 0 reason for that, she was free to make them both adults and STILL work on the morality of "fated partners" or whatever fucked up shit they're experiencing. Nothing would've changed the story's main purpose (learning self-control, consequences of this universe, etc.) unless there's another reason attached to having a 17 year old shoving a dildo up his ass, being aroused, and kissing a 8 year old kid while having the deepest monologues about loving him, but you are not ready for that discussion yet.
A story rated 18+ shouldn't have underaged characters.