Mao had a photobook released when she was 16. We learn a bit about her past activities that she does not mention now. Not revealing at all, though.

'Her beautiful features make you fall in love at first sight This is the first digital photobook of the promising 16-year-old Matsumoto Mao! The location was somewhere in Tokyo, and I was amazed at how beautiful she is It feels like the air is crystal clear only around her She's a girl to look forward to in the future, so be sure to check her out! Oh, and don't miss the NTT Docomo concept movie! You can see her glamorous classical ballet, which she has been doing since she was 4

"PROTO STAR" A digital photobook series featuring beautiful girls who are sure to have a great future!'

https://www.amazon.co.jp/PROTO-STAR-松本真央-vol-1-ebook/dp/B073GLDKNX/