Age: 16
Birthday: May 1st (Taurus)

A first year student at Ohananomitsu High School in Class 1-4 and the protagonist of Kimi no Koto ga Daidaidaidaidaisuki na 100-nin no Kanajo. From 8 months old to his junior high graduation, Rentarou has experienced 100 love proposal rejections in a row, he is eventually told by the Love God that, due to an error he made at Rentaro's birth, he has 100 soulmates that he will soon meet. He constantly works to be the best boyfriend he can, tempering both his body and mind.

Rentarou is a kind, thoughtful, serious, and sociable boy who is easy to get close to. He knows how to study well and is relatively athletic. Rentarou genuinely loves all his girlfriends more than anything else, and is very easily impressed by their actions, especially when they do things that he finds cute. However, Rentarou is also very protective of his girlfriends and often needs to be calmed down should someone insult or harass any of them, hinting at a somewhat short temper. There have been times where he almost got into fistfights with people when they insulted or slighted his girlfriends, or he feels that his girlfriends are in danger.

Not only that, but on multiple occasions he has displayed loyalty and isn't dirty-minded nor willing to do anything that his girlfriends don't want.

Name/Birthday Pun Explanation:

Both the Ai (愛) and the Ren (恋) in his name are spelt with different kanji for love. His surname Aijou (愛城) means "Feelings of Love".

Rentarou's birthday is on May 1st. With Goroawase, 51 can be read as "ko(5)i(1)", the word for "love" (恋). Due to this, this day has also been called "The Day Love Begins (恋がはじまる日) (Koi ga hajimaru hi)" and "Premonition of Love Day (恋の予感の日) (Koi no yokan no hi)".

(Source: 100kanojo Wiki, edited)