ぐ
おろ
None
If you give Splinter your heart you'll feel pretty foolish afterwards. His heart belongs to the art of ninjutsu!
Splinter tells you to your face how foolish you are and you feel your heart turn to goo (ぐ). Now you can't even give it to someone else. No one wants goo.
Currently there are no similar looking kanji which exist in the WaniKani learning system