Mononoke no Ran

Every day, when he returns home, he is attacked by his grandfather on the pretext of training. Shizuka Pengichiro, a descendant of a venerable ninja clan, is a first-year high school boy who wishes to escape this crazy routine. Because in today's peaceful world, there is no need for ninjas anymore. Trying to escape from becoming a ninja, he sacrifices his high school social life in order to devote himself wholeheartedly to his studies. Until an encounter with Mikogami Kyoka, a girl who calls Pengichiro "'a man of destiny," changes his peaceful life forever. The ninja and the onmyoji will team up and begin their supernatural crime-fighting quest in Kyoto!

(Source: Weekly Shonen Magazine, translated)