Itsuki Myoudouin is a notable female bearer of this name. She is a main character from the 2010 Anime series "Heartcatch Pretty Cure". Her alter ego is Cure Sunshine.
Itsuki is also used as a feminine name in Japanese. However, it's more common for males. So, I think that the "Gender" of this name should be changed from "Masculine" to "Masculine & Feminine". Also, according to the source below, "from the late 7th century to the 14th century, an unmarried princess of the Imperial Family, called "Saiō" (斎王) or itsuki no miko (斎皇女), served as the sacred priestess of Amaterasu at the Ise Shrine upon every new dynasty.[107]"Sources: https://en.m.wikipedia.org/wiki/Itsuki https://forebears.io/x/forenames/itsuki https://en.m.wikipedia.org/wiki/Amaterasu
Itsuki is the name of the shopkeeper in "Soullessly" and "Soullessly 2".
― Anonymous User 1/12/2019
1
Itsuki, used as the kanji "樹" is currently 4th place in Japan, in terms of kanji and Itsuki used as "いつき" is 33rd place in terms of sound. (source: http://5go.biz/sei/cgi/ninki1.htm).
Itzuki Yamazaki or Itsuki Yamazaki is a retired Japanese professional wrestler who is best known as one of the tag team Jumping Bomb Angels with Noriyo Tateno. She worked with All Japan Women's Pro-Wrestling, World Wrestling Federation, World Championship Wrestling, and Japanese Women's Pro until she retired in the end of 1991.
Itsuki Toyama is a Japanese politician, an independent member of the House of Councillors in the Diet (national legislature). He was elected to the House of Councillors for the first time in 2007 after running unsuccessfully for the House of Representatives in 2005.
Itsuki Shoda is a Japanese baseball player for the Lamigo Monkeys. He was originally drafted by the Nippon-Ham Fighters in 2000, playing 5 seasons, before playing for the Hanshin Tigers.
This COULD technically be used on a girl as well with different kanji. It doesn't seem like a super-common name these days. I would use Itsuki on a girl using the kanji 生連基 and it probably never would have crossed my mind for a boy. That said, ki can be an ending for names of either gender... though certain kanji are more likely to be used on 1 gender or the other. However, I guess the kanji I have here could probably be used on a boy as well.