This is Hikaru's youkai grandfather Toshi. As you can see, Hikaru takes after him when it comes to hairstyle. Yes, Toshi's eyes are totally green like that. He's a lot more powerful than Hikaru, and he can change his appearance so he can fit in with normal humans if he likes. This is also where Hikaru's fire abilities come from. Toshi is rather nasty when it comes to wielding the fire. Look for more of Toshi in the future!