Good manga, but ending is somewhat bad. Basically there is some major conflict that will affect fate of multiple worlds, but this series ends with almost no explanation at all. It's like that global conflict is there just to put character in combat situations, and not as an actual well-thought-out story. Some characters important to that conflict appears only once, talk some obscure lines and never seen again. It seems author can do another side-series just to explain the lore and fill the missing gaps, if he cares. It needs much better world-building.