I don't mind isekai manga, but the protagonist's set up doesn't mesh with his personality. If he was a sage and a hero in his previous life why is he so oblivious as to what is powerful and what isn't? I would understand the ignorance is bliss trope if this was his first time, but it isn't.
It's not hero and priestess but it has a similar comedic dynamic. The priestess isn't as head over heels for the hero but tries their hardest. If I recall the priestess reminds me of Aqua from Konosuba in a way.
Thanks for any help.
Edit: Found it, if anyone is curious it was Alicia's Diet Quest.