Kyosuke is the male protagonist in the love triangle. He and his siblings have supernatural powers, referred to in the series as "The Power", and are described as espers in the series. They are forbidden from using their powers in public, lest they be discovered and exploited. In each instance where someone has seen their powers, the family has immediately relocated.
Kyosuke's esper powers include teleportation, telekinesis, and "time-slipping" (a kind of a time travel) while falling from heights such as stairs. He can alter mechanical devices such as elevators and traffic lights. He can direct his powers to his ears to amplify his hearing and he has also demonstrated a hypnotism power as evidenced when he hypnotized himself to be more decisive.
Kyosuke is also rarely shown to use his powers to temporarily amplify his speed and strength. On very rare occasions—generally, when Madoka is directly threatened—his power has taken the form of raw energy that can shatter concrete walls or short out every light in a disco.
Kyosuke is a pretty gentle person and a bit of a goody-goody—when he sees Madoka smoking, he scolds her in a very nerdy way (and then uses his powers to destroy her cigarette). It is his indecisiveness that leads to the love triangle with Hikaru and Madoka. He is initially unable to decide between his feelings for Hikaru and Madoka.
As the story progresses however, he find himself unable to end the relationship with Hikaru for fear of hurting her feelings and destroying her friendship with Madoka.