Kiku is indeed also sometimes (albeit rarely) used as a masculine name in Japanese. And I'm not saying this just because of the character Honda Kiku from Hetalia (I am aware of the naming situation there). According to forebears.io, there are male bearers of this name in Japan. However, this name is more commonly used for females. So, I think that the "Gender" of this name should be changed from "Feminine" to "Feminine & Masculine".Source: https://forebears.io/forenames/kiku
Source: https://forebears.io/forenames/kiku