Well, episode 11 eluded to him having a sibling but the way he said it, it made it sound like the baby didn't make it.
@Evilcleo, exactly! therefore for me, its a joy to see that in the manga here since (unless i'm wrong, do correct me) i don't even remember him stating if it was a girl or a boy sibling he had
OMG! Definitely, DIFFERENT FROM THE ANIME ALRIGHT! XD KEITA HAD A LITTLE SISTER?! HAHA, SHE'S SO FUNNY AND KNOWS "BL"?! XD Gonna protect her big brother from Kazuki! Hehehe, you go Tomoko-chan! <3