Kirika
Kirika is the leader of the eiken club. She is a purple haired amazon of a girl with 99cm G-cup breasts.
She is the one that forced Densuke to join the Eiken club because, according to her, he had no skill and lacks noticability, and has tormented him often since; often using her breasts to tease him through either smothering, using his head to hold them up, hitting him with them or just deliberately giving him a peek. She has also been known to use her butt to hit Densuke with great force as well.
She has little to no inhibitions, she does not wear underwear unless as part of a bikini, and has no problem tackling Densuke while both she and him are totally naked. She also has no problem with groping Chiharu which she often does to tease Densuke.
However when she is sick or suffering from allergies her personality competly changes. She gains inhibitions her normal self never has, such as feeling of embarrasment from her usual revealing attire, and enjoys girly and somewhat childish things, such as the childrens cartoon character Nekomanman. While sick she also has lapses in memory, when sick she forgets what she was doing before she became ill, and when she becomes well again she forgets almost everything from when she was ill.
She can often be found eating foods which are phallic symbols.
Kirika has also claimed that she likes Densuke, although this might just be teasing. Considering that almost every main or secondary female character in the series likes him to at least some degree then it's not too unbelievable she might as well. Her constant teasing could also be seen as trying to get him out of his shyness. She also seems to be playing matchmaker from time to time between Desuke and Chiharu, often whispering into Densukes ear about Chiharu to deliberately get his imagination to run wild and is quite often the cause of the perverted positions Densuke often finds himself in.
Very little is known about her personnal life, the club member profile that Kyoko created for her only has her name.
In the OAV she is voiced by Masumi Asano in japanese and Cindy Robinson in english