They're crystallized stones within the body that cause blockage to the passage of urine.

As the pressure accumulates, it brings unbearable colicky pain (abdominal pain).

It holds the title of "The King of Pain"!

Do you feel like vomiting?

I couldn't draw blood from this patient-usa.

This is the third attempt to stab-usa.

D... doctor...

You got it wrong...

This pain

is because of Koishi- Koishi literally means "small stone".

I'm not letting a single drop of pee through!

That'll hurt, that'll huuuurt~

Okay, I'm inserting the IV needle.

This is going to sting!