Zanryuu Shinen (残留 思念) is the true villain and final boss from Shikigami no Shiro. Once the Girl is defeated, it finally manifests itself for the final battle.
Background[]
Shinen appears as a skull-shaped purple ghost. It is impossible to hit him, so the only thing you can do is survive until he depletes all of his energy. He uses the regular shots in circular patterns and large blue flames, also being able to shot a huge frontal laser. He will shrink in size as the battle goes on, exploding when he is finally exhausted.