Responses
this is why isekai romance is complicated.
Adult Mc in a child body + a child of his own age on the current timeline = bad
Adult Mc in a child body + an adult of his own age like his past timeline= also bad
That's why I'm an advocate of never putting romance in a perfectly good regression(specifically back to a child) anime or manga.

mc confess love to teacher as a child
fcuking dropped