Saitei Rank no Boukensha, Yuusha Shoujo wo Sodateru Orette

Synopsis:

Meet Kousuke Igami, an unpretentious moderately aged man, usually seen as just a placeholder in his everyday life. In any case, underneath this conventional veneer conceals an unforeseen reality: he is, as a matter of fact, an incredible explorer! As predetermination would have it, he ends up tutoring a gathering of hugely gifted and captivating young ladies.