Calling Out to Brother from the Center of the World
As Shūsuke puts up with more of Ran's dubious rituals, Rin forces Nao to hang out with her by threatening to tell Shūsuke that she had been stalking him, looking for an opportunity to kiss her. Shūsuke and Nao soon become paranoid around each other when they see each other hanging around the respective Yatagai sister. Nao and Iroha determine that the only way to get Rin off her back is to convince Ran that Shūsuke isn't her saviour by pretending to be prophets on their mobile phones. Rin catches onto their plan and tries to get the drop on Nao but ends up kissing Iroha instead, though she immediately takes a liking to her lips and runs off with her. Ran later explains to Nao that she wanted to mentally train Shūsuke to play as a warrior for a cosplay event, though when the day of the event arrives, Shūsuke gets the address wrong and arrested for wearing his skimpy outfit in public.
Aired 20/03/2011EP 11 - Calling Out to Brother from the Center of the World

I don't like my big brother at all!!
Junior High student Nao's brother complex is so strong, it's almost at the point of incest. She's determined to make her brother, High School student Shuusuke, see her as a woman. So determined, that she goes as far as going into his room to throw away all his non-incest related porn. But as she's looking for his porno stash, she finds a photo album... and she's not in any of his childhood pictures. What is going on?