Kaien has always been confident, charismatic and the life of the party. He despises boredom but knows that waiting has an equally high chance of bringing adventure to you, especially in the wild places he prefers to hang out at. Despite this, his friendship his childhood best friend Marshall always comes before looking cool or having adventures. Trouble is known to find his best friend anyway.
His carefree life changes rather abruptly when he visits Marshall only to find that he has adopted a baby Symphony named Mereille. Knowing that Marshall can't possibly take care of a baby by himself, especially since he can't say no to the child and is rather like one himself, Kaien moves nearby to keep them both out of trouble. Suddenly this popular and charming rogue has become a father. As much as he feels put out at the beginning, as much as he pretends to hate it, Kaien comes to love Mereille and he wouldn't change his current situation for the world. Not that he would ever admit it.