«Я девушка-монстр, которой вы помогли в тот раз»: Перерождённый учитель-старик в замешательстве от внезапной популярности
Some 20 years have passed since the protagonist was summoned to another world and retired from the army. He is still single in his 40s and lives as a low-ranking professor, until one day, an elite "monster girl" transfers into his class.