Rumi Shishido

Beautiful sisters Ai, Mai, Mii, their android maid Mea and slippery pet ferret Unagi make an amazing journey together through time and space without ever leaving their beloved mansion behind! Following the clues of the strange dandelion-like "Popotan," the girls are theoretically seeking the person who has the answers to their most personal questions, but they seem to have more than enough time to take side trips, meet new friends, visit hot springs and occasionally operate the X-mas shop they keep in the house along the way! Yet, the girls' ultimate destiny holds more than a few surprises of its own, and not every moment is filled with hilarity, as moving through time means having to leave friends behind as well. (Source: RightStuf)

The year is T.C. 4767. Four thousand years have passed since humanity abandoned its birthplace, the planet Earth. Beset by the hostile alien Gnosis, mankind is now scrambling to find ways to defeat this threat to their existence. The development of KOS-MOS (a specialized android with amazing capabilities) by Vector engineer Shion Uzuki was one response to the threat. But when their ship is destroyed by the Gnosis, Shion and her companions find themselves thrust into the middle of a battle with no clear sides... (Source: Anime-Planet)

A 15-year-old girl has a goal of bedding 100 boys. The trouble is she's a virgin who knows nothing about dating, relationships, or sex.

The series is set in the distant future in which the Earth is split in two. The southern hemisphere is placed in another dimension while the inhabitants of the northern hemisphere are able to morph into beast-like humanoids. Eventually the humans of the southern hemisphere, led by Uranus, attack the Beasts. The Three Beasts, Wan Derbard (Wan Dabadadatta) of the Tiger Tribe, Bud Mint (Baado Mint) of the Bird Tribe, and Mei Mer (Mei Mah) of the Mermaid Tribe, are taken prisoner along with Mei Mer's companion Tuttle Millen (Mekka Mannen, also of the Mermaid tribe), but manage to escape thanks to a little girl named Yuuni Charm Password. Together they seek Gaia, which they believe to be a fabulous treasure, but they are pursued by Uranus's minions : V-Darn the vicious mage-knight, V-Sion the warrior woman and Akumako, V-Darn's sadistic imp-like partner. (Source: Wikipedia)

The two Nanas are still sharing an apartment in Tokyo, but Nana Komatsu's boy troubles and the success of Nana Osaki's band tests their relationship.