Not totally sure if this watercolor, because in the media section on pixiv, or whatever you wanna call it, my machine translation says watercolor pencil. However, as per the wiki, this 透明水彩 appears instead of this 水彩色鉛筆, so could someone go ahead and double check.

That's because you translated the two words at once.
Pencil lineart and watercolor coloring. No worries.