So, even shadow-y evil organizations still need incentives for people to risk their lives for them, and the biggest flaw with this manga is that I can't see any reasons for the evil minions to follow the big baddie. The big baddie, Touma, is a yandere who basically wants to destroy everything that fe sees as getting between fem and our main character, Setsu. Feir motives are extremely personal, so I can't imagine feir followers sharing feir goal. And who would risk feir life for somebody else's romantic insanity? So that's a major plothole: the die-on-their-sword loyalty these minions are showing to their leader for no apparent reason.
Setsu usually can beat anybody with just a flick of feir finger, but in cases when feir brute force doesn't work, fe solves them by using feir sword Gluttony which can eat anything--even metaphysical concepts like "death." I don't find the fights very engaging. And beyond the fighting, the main hook is showing all the women who are devoted to Setsu (from the previous time fe was in this world) and showing fem accumulating new harem-mates as fe travels to the demon and beastkin continents. I also don't find the harem very engaging, since we're not shown growth within the relationships.
[Reviewed at chapter 16]