じゃく, せき
さび, さみ
None
On the roof above, is a small stool. Anyone who sits in that stool will be lonely.
You're so lonely, you make up an imaginary friend: Jack (じゃく). Jack doesn't get rid of the lonely feeling because he isn't real, but he is a distraction at least.
Currently there are no similar looking kanji which exist in the WaniKani learning system