Here's a fun item for all cosplayers, including otokonoko fans: Cow Print (Ushigara) Arm Covers. They allow you to have cool un-attached sleeves like Hatsune Miku, which looks cool. They protect you from the sun while making you stylish and awesome!
The package features ero vtuber Sopra Nemugaki, aka Sopra Amane.
This is presented as an "otokonoko" cosplay item but it's able to be used by both men and women.