Max649kemp

Hi all, Im trying to find this anime series i watched a few years ago but can not find it. My memory of it is ropey but i do remember really enjoying it and a few little bits Mainly in the first scene the main characted, a boy, is woken by his 'top heavy' little sister jumping on him... bit wierd i know. Also i feel like at one point he ends up in a dojo full of female fighters If anyone has any idea please let me know