An old classmate Yuriko, remembers her time watching Natsume and how he was a little weird.  A clingbug from Natsume’s past reminds him of the time he spent running from a youkai with a grudge.
It's weak so it protects itself 
by clinging to humans.
Al ser débil se pega así a 
las personas para protegerse.
Como es débil, se pega a los humanos para protegerse.
É tão fraco que se prende a
 humanos para se proteger.