 If you liked
Nigoru Hitomi de Nani wo Negau: Highserk Senki
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 ...then you might like
Sensou Kyoushitsu
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Sensou Kyoushitu (the Bugle Call) and Record of Highserk War have a similar style of medieval fantasy grounded in actual medieval battle tactics with strategic use of magic/special abilities. The worldbuilding share similar elements as well, with fictional countries at war in a medival europe like setting.