AIKa R-16: Virgin Mission

If your main reason for watching Ikkitousen was pantsu-filled action (or action-filled pantsu?), you might like this too. You'll really have a hard time finding a fighting scene without any, not with all those weird angles, moves, and poses. 

They share the same comedy + ecchi based story style Both have some missions and the actions are mainly performed by young female. Asobi ni Iku yo is more random. It is bundled with UFO & catgirl aliens, with a protagonist and a harem; while Aika is female centered with a secret mission to complete per series...  

Action with pantsu. Also have weak characters. WARNING: High School of the Dead has zombies and more gore. 

Created by the same director and animation studio. It is Katsuhiko Nishijima one diversion into making Ero titles. The character design of Risako-sensei seems to come from the design of Rena in Lingeries. Lingeries was made about 6 years before AIKa R-16