Rumi and Naori are twins but have nothing in common, except their feelings for Jun, their next-door neighbor.

It's time for the twins' birthday, with well wishes and gifts coming from various people, even unexpected ones!

Jun and Naori go on a date to a familiar location, which gives Jun flashbacks to when he was there with Rumi.

Jun decides to help Shiena with her studies, which drives Naori crazy. Rumi, on the other hand, seems unusually indifferent about it. However, for Naori, it's clear that she needs to keep an eye on them. So, she quickly invites herself along.

Naori puts her plan of making a new club into action, and in the meantime Rumi receives some unexpected news.

The negotiations over the empty clubroom begin, while Rumi's situation with Mizumi grows more complicated by the second.

After dumping Jun, Rumi makes another request of him, one that he couldn't have seen coming.

Naori explains herself and her reasons to Jun and Rumi in order, leaving them baffled.

Jun has decided not to get involved with either of them for the time being. A friend of Rumi asks Jun to help her with studying. They try to keep this a secret from Naori since she is a stunningly beautiful model.

After seeing Mizuma's message, Jun has a decision to make about Rumi. Meanwhile, Naori is plotting something after her chess game, too.

Naori intercepts Jun at his door and asks if she can stay over at his place. And in the current, complicated situation, the Shirosaki and Jinguuji families go camping together.

Jun, Naori, and Rumi have to come to terms with their new dynamic. Jun goes to Toyoshige for advice.