This book, as a spin-off, revolves around Aoba-senpai aka. Watarun from Sankaku Twilight. Wataru needs enough credits to graduate from high-school and his teacher makes him pair with Yugo who is freshman to clean up the school grounds. Even Yugo is cocky and uninterested, Wataru still tries to be friendly protective senior for him. One day when they argue on something, both of them accidentally witness a moment of Miki and Ikkei. As a childhood friend of Miki, Wataru, asks Yugo to keep this as a secret from others but Yugo asks for a request in return. This request will change their all dynamics inthe future.

It was a common extrovert senpai x introvert kouhai story but still has its own charm after connecting with the main book. After main book, seeing funny and clumsy side of Aoba-senpai was pleasing. I like how author connected Yugo's and Wataru's issues in similar perspective. Also, having Ikkei and Miki as side characters was enjoyable.