The Treasure Hunting Club is a club formed by Eri Shinkai with her parents' money to explore the world.
Eri is the founder and president of the club
Midori, Aki, Kyoko
Midori, Aki, and Kyoko are the first three members that join the Club, even before Aika Sumeragi and Karen Minamino. Despite these credentials, they quicky see themselves replaced as Eri's liutenants by Karen and Aika. Their bad luck continues when, as soon as Episode 1, they are knocked out by Risako and implanted with mind control microchips that leve them under her total control. This turn of events suddenly leaves them as enemies of the Club, and the poor girls soon find themselves being mercilessly put down once more, this time by Aika and the Captain. After their defeat, they are stripped naked and taken to the Medical Bay, where they are left under surveillance till the mind controlling implants wear off.
Due to this rather unfortunate chain of events, the three girls get to experiment scarcely any part of the adventure, spending most time unconscious or getting their asses kicked by someone.
Six girls who join the Club afterwards, to raise the total number of members to 12. They serve little puropose besides being cannon fodder and fanservice material. In Episode 1, Risako and Kyoko make quick work of all of them as they kidnapp Karen, leaving them sprawled on the floor unconscious. In Episode 2 they encounter a similar fate, being put down by a sniper as they try to relax at the beach. By the end of this last chapter, Eri, Karen and Aika make the smart decision to just leave them behind resting and go on by themsleves.