There are eight sufferings in the world: birth, old age, illness, death, separation from love, long-lasting resentment, not being able to get what you want, and not being able to let go. The most poisonous thing is not being able to let go of something you want, and Platycodon may be like this to Naraku. You can't want something but can't let it go. It becomes a thorn in the heart that can't be pulled out, and it can't be said.
Conception: