Chapter 1

Experiment #1: Rokka-kun (実験その1: ロッカくん) is the 1st chapter of Ueno-san wa Bukiyou.

Plot
Tanaka, a second year middle school student, is late to his Science Club meeting. The club president, a third year named Ueno, has a brilliant new invention, Rokka-kun, that can purify any water source to be pure H2O.

Ueno wants to test it out on Tanaka by giving him a beaker of her purified urine to drink. Tanaka is grossed out at the idea, and refuses to drink it. Ueno gets a first year named Yamashita to test the water first, paying her to participate in the experiment. It tastes and smells like regular water.

Ueno is persistent in getting Tanaka to drink her pee. Because she wants him to take it as a confession of her love for him. Tanaka is too naïve to understand what's going on, so Yamashita jumps in to explain Ueno's feelings.

But Tanaka is too dense to understand even when being told outright he is being confessed to. Tanaka leaves for home, and Ueno and Yamashita are left frustrated. Ueno has been in love with Tanaka since the end of her second year, but nothing she has tried has worked on Tanaka. But she likes his obliviousness.

She plans to put some of her purified urine in his food tomorrow and announcing it over the loudspeaker. Yamashita tells her she's evil.

Cast
Ueno

Tanaka

Yamashita

Trivia

 * Ueno and Tanaka look slightly different from their final design. Ueno has much shorter twintails than her later design. Tanaka has a thinner face and somewhat longer hair than his later design.
 * This is the only chapter so far where Tanaka can be seen wearing his school tracksuit. It can be seen in Ueno's flashback to her popping out of a large present at Christmas.

Title
In Japanese, the words for filtration and the name Rocca sound similar.
 * 濾過→ロッカ