When Hiro was in high school, he had many part-time jobs in order to protect the house. One time, one of his high school friend got a dog, and he decided to get one because he was lonely in the big house. However, when he checked the price, it was too expensive, so he couldnt get one. And instead he thought he would get a turtle instead, Wakaba.
He first appears under the mess of clothes Mao dumped on the floor causing her to yell in surprise.
When Mao confesses to Hiro that she likes her, Hiro nervously tries to avoid the topic by admiring Wakaba's soft paws while still blushing furiously. He later appears on Mao's bed when she's trying to recover from her fever.
Wakaba appears to have a rather calm personality and enjoy human companionship as he doesn't struggle or run away when Mao or Hiro plays with him. He is also used to being picked up since both Mao and Hiro carry their pets reguarly at home.