Train_Man: Densha Otoko

Boy–bashful and not overly brave–defends girl from obnoxious drunk on a Tokyo train. Girl sends boy a thank-you pair of pricey Hermés teacups. Boy's a geek and doesn't know what to do next. End of story for most nerds–but this one turns to the world's largest online message board and asks for help, so for him it's just the beginning. This matchless love story is told through a series of Internet chat room threads. As Train Man, our hero charts his progress and unveils each new crisis–from making conversation to deciding what to wear on a date and beyond–in return, he receives advice, encouragement, warnings, and sympathy from the anonymous netizens. And Train Man discovers the secret to what makes the world go round–and proves we really do live in a universe where anything can happen.

After establishing contact with extraterrestrial civilizations, it was found that humans were the only race to develop various sports. The number of alien sports fans grew dramatically, and the most fanatic of them regularly harass stadiums for taking part in a game, or demanding a good show, etc. Finally a treaty was settled, ruling all interferences towards other planets' cultures illegal. Rabbit Force, a group of rabbit-themed henshin girls, became responsible for enforcing the treaty and capturing any offenders. (Source: AnimeCouncil²)

It's about an Otaku guy who fell in love with this beautiful lady and tries his best to get that girl with a lot of help from 2channelers (people who goes/posts on 2ch). This story has become very famous in Japan and I believe they now have novels, several series of Manga (both Shoujo and Shounen), movie, drama, play, etc, etc.

Geeky fanboy Ikumi Saiki has a dream that someday, somehow, he'll finally get a girlfriend. Then one day, on the train home, he rescues a beautiful girl from a troublesome drunk. Now the girl sees the hero inside the otaku -- and it appears that Ikumi will finally find romance! But though Ikumi found the courage to save her, will he ever be brave enough to win her heart? Desparate, Ikumi posts an urgent plea on an Internet message board: "Help me with the girl of my dreams!" Ikumi's story ignites the whole online world. Everyone is ready to help Ikumi prove that even an otaku can find true love! (Source: Del Rey)

Perpetual geek, social basket case and obsessive fan – needless to say, the guy called "Train Man" has never had a girlfriend. Most of his days are spent immersed in electronics and waiting for the box set DVD of his favorite anime series. But fate takes a turn for Train one ordinary night on an ordinary train ride. He falls in love at first sight with Hermess, a gorgeous fellow passenger. When a drunken rider tries to harass her, Train surprises himself by coming to her rescue. But when Hermess later contacts Train with a thank you give and the possibility of further contact, that's one situation he can't handle. He immediately goes online to a popular chat room to solicit advice. To his horror, he's encouraged to ask her out. Soon he is bombarded with advice regarding how, when and where he should do it. Will Train Man find true love, or will all this pressure to come out of his shell be too much for him to take? (Source: CMX)