What could go wrong with the cute couple this episode? It's still a mystery... but first... Takeo saves a life, literally, again, this time a little boy who almost drowns. Suna gets the thank you again, but Suna tries to set the record straight. It makes no difference though.
We also met Suna's beautiful older sister, Ai, who unexpectedly, has a crush on her little bro's best friend, Takeo. She does not take the news that Takeo has a girlfriend very well.
She "accidentally" meets Takeo, Suna, and Yamato at the park (she stalks Suna by GPS) in order to inspect Yamato. Yamato says how beautiful Ai is, and Takeo says how kind Ai is as we see her wipe Takeo's nose as a child in a flashback.
In a cute scene, we see Yamato offer up her latest cooking creation of cookies. Turns out she mistook the salt for sugar and they are terrible. But Takeo doesn't bat an eyelash. It's all good as long as Yamato made it. Aw. As Ai observes Yamato, she notices she is hiding something. In fact, the main "problem" of the show is that Yamato is hiding something from Takeo. Takeo finally notices it himself and tries to figure it out by reading a teen magazine.
Ai runs into him (in a real coincidence this time) and stops him from this embarrassing behavior by promising to help him find out what Yamato is keeping secret.
It seems like Yamato is troubled every time Takeo says how "pure" she is or states that he won't lay a hand on her until she is an adult. Maybe Yamato wouldn't mind at least holding hands or something...