This is an interesting isekai series with dark fantasy feel to it. High school student Kurono Mao is transported or rather abducted into different world, where he is experimented on using dark magic in order to turn him into some kind of solider . This beginning already sets in the dark and gritty feel to the series. The MC is trained to be strong, but is far from the strongest. He is set on the path, where he has to fight the theocratic kingdom, which abducted him for world conquest .
The MC is driven by revenge and desire to protect people, who befriended him, from genocidal conquest of the theocracy. While the MC is quite strong, he is still far from the strongest. It has kind of fighting shounen feel to his journey, which seems to go in direction of him growing stronger. The series doesn’t hold back on violence and it is not afraid to kill off any side character. Aside from few powerful antagonists there are also introduced side characters, which constitute MC’s party. First is half-fairy Lily. She really wants to be the chosen girl . The second is powerful mage/witch Fiona. She is bit timid and her primary concern is eating. She has strong magic power, but it is very hard for her to control it in a way to avoid friendly fire, which concerns her greatly.
Art work is not the best/masterpiece, but it is still pretty nice. I would say it’s above average. I’ve bought digital version. It has few pages at the beginning in full colour.
Japanese difficulty 5/10 (see my profile for details about various difficulty scores)
There is almost no furigana in the series. It consists mostly of average difficulty, with fantasy themed language. A bit difficult and unusual are catholic clergy titles used as titles among theocracy nobles/officials. I find it bizarre to use such terms in fantasy settings, where it is devoid of its original meaning, but I digress.
So far, I do enjoy the series. I’ve read all existing volumes in one sitting. It is one of the more refreshing takes on isekai imho.
This review is written after reading 6 volumes (all existing at the time).
 He grows stronger and eventually manages to escape from the facility before he is brainwashed to be obedient slave.
 The theocratic kingdom is about to invade continent of kingdoms’ where demi-humans live. MC manages to escape there and builds friendship with demi-humans especially half-fairy Lili.
 Surprisingly her character is shown to be yandere. Especially when MC is not around, she can go really crazy.