Self
こ, き
おのれ
None
The kanji and the radical are the same, so remembering the meaning of this kanji is as simple as making sure you know the radical for oneself first! If you know the radical, you know this kanji means oneself as well.
Oneself. Who only thinks of oneself? Every 子 (こ) in the world.
Currently there are no similar looking kanji which exist in the WaniKani learning system