頑張 がんばろっちゃう
gambaro' chau

Godan Verb (u)
Interjection

The completive aspect (contracted form) - indicates completion or regret of 頑張ろう

1. Let's try.; ; I'll do it.; I'm going to end up doing it.; I guess I'll do it.; I'm stuck doing it.

Completed Action
Colloquial