@Zikakuto
That man needs some baby powder for his grundle... He was hoisted so quickly by his own petard, he's surely bruised. Pride is one of the seven deadly sins for a reason.
Resigning in Japan is a big deal. More than likely it would be impossible to get another job with that on your record. Essentially, it killed kouhai-kun's career. That explains the high level of guilt with senpai.
@Newblood80 it's his own kouhai's fault though. He's just being impatient, basically he's a newbie at work who wanted to immediately do the big things, while never even actually aced what he think of 'grunt works'. Also senpai have been trying to tell him that but Kouhai-kun cut it short while acting so pissed off on his own, he won't listen to reason with that high and mighty attitude.