Kokushibo

Kokushibou and Yoirichi are brothers and they have a beautiful sister Vika. Vika has hair like Yoirichi and eyes like Kokushibo and the character of both of them but Kokushibo became a demon. Yoirichi knew this but did not tell Vika. Since then, Vika lives with Yoirichi and Vika is also a demon hunter and so Vika and Yoirichi walked down the street together and accidentally ended up in an endless castle and there they met Kokushibo who had already forgotten them

Hello