The Magic in this Other World is Too Far Behind! Volume 9 by Gamei Hitsuji

Suimei has finally figured out a way to get home, but it’s too soon to celebrate. Suimei’s return to his own world is less of a homecoming and more of a pit stop on a much larger and much, much more dangerous journey. Suimei needs to amass as many allies and resources as he can if he has a prayer of defeating his nemesis once and for all... But that’s going to get a little tricky if he’s babysitting the entire time. The girls are in for a surprise in this world where science is king!