Because I Don't Like My Big Brother At-All--!!

Season 1, Episode 12: I Don't Like My Big Brother at All!!

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Shusuke and Nao are left alone in the house when their parents go on an overnight trip. Nao takes the opportunity to try and seduce Shusuke by wearing a maid's outfit as he tries to prepare dinner. After washing up after a little accident in the kitchen, the two become paranoid when Nao starts hearing strange panting, which turns out to be the AGE Explorers, who invite Shusuke out on an unsuccessful search for porn, which gives him a cold. As Nao tends to it, Iroha and Mayuka pay a visit, which once again turns into a battle for his attention.