Release date: 2012/12/15 Recording time: 25 minutes Circle name: To Jiboro Banni Subject: Original series: Echi secret base "Can you call me Onii-chan?" Twin tail girl who met in the country's summer vacation, Kotone chan! We began to play together everyday. "Kotone chan, I will tell you my secret base!" Daily innocence at the brother's secret base starts now! !