Shijou is another schoolmate of Komaki. Introduced right after Kurokawa, he appears to be weird when it comes to sex. He's shown to having sex with many different girls and them dumping them, against their will, after a kiss which he doesnt like later. Tomoaki Shijou is very similar to Kurokawa due to reason like "kids" and not making much difference between males or females.
Hana soon confirms that he, in fact, has an alien in sleeping-status, inside his head like the other main characters. His ability is a high sensitive taste: with a simple kiss he can understand if a girl is pregnant or fruitful, still by only tasting any food he's able to cook them and understand the exact dosage of any things in them. As Komaki states, he's a good cook. The reason behind his weird behaviour with girls which he had sex with, is explained to be that he wanted to have a baby 'cuz his young sister wanted a little sister. Shijou is orphan, and as good big brother, always took good care of her little sister Moe. In truth he's a really sweet guy which simply doesnt realize yet, the big things that sometimes his sister ask him to do.
In the middle of the story Shijou becomes Komaki's new boyfriend after Takayama, and b'cuz of this he wont have a good friend relationship with Tsurumi. The boy seems to be the one that less-cares about the Aliens story between all the guys, in fact his only preocupation is always be his sister and her wills; and later to make Komaki's happy too.
However his love relationship with Komaki sees and end when she realizes to be in love for Tsurumi. Althought, Shijou shown to be really in love for Komaki this time, unlike all the other girls he slept with just to have a baby. It's been said by Komaki that his smell makes her really comfortable and probably was this the cause which she liked him at first. Ikeno realizes that he still reason like a child and 'cuz of this she's the only one able to explain him things the way to let him truly understand.