Nanamori (ななもり。), real name Masato Kashiwabara (柏原真人, Kashiwabara Masato)[2] is the leader of Strawberry Prince and CEO of STPR inc. He started live streaming on June 25, 2013[3], and he started covering songs in November 2015, starting with Umetora's "Koshitantan". He mainly uploads song covers to his YouTube, but he also live streams and uploads some gameplay videos.

Along with singing, he can rap and beatbox. In some songs, he writes the lyrics, sometimes with Root. He often collaborated with PMaru-sama, being her partner in comedy skits. The two are very close, playing games together and also having collaboration videos together with Jel. He does many things to support StPri behind the scenes on top of his online activities.

Colon says in an interview that Nanamori is quick-witted, to the point you'd think that he'd been reincarnated at least 3 times. He is seen as StPri's mother, and the person that the members go to when they have troubles. According to Root, Nanamori's advice is like a revelation from God. He normally has a kind presence and is hard to make angry, as seen in three unsuccessful pranks done by Riinu, Root, and PMaru-sama respectively.

In March 2022, he announced that he would be going on a hiatus following claims of infidelity, but would not resign as CEO. In December of that year, he announced that he would resume his activities as an individual and support StPri from behind the scenes. In January 2024, he and Jel officially returned to StPri.

He is portrayed with neat, dark purple hair and an ahoge at the top of his head. The sides of his hair slightly curve to the side. From 2015-early 2018, his hair was deep brown, and much neater.