Party kara Tsuihou sareta Sono Chiyushi, Jitsu wa Saikyou ni Tsuki

A healer gets booted from his party because the leader notices he isn't really contributing much to the team. Soon enough, the healer must look for new members to party with. After finding a cute martial artist to work together with, he reveals his secret: while he's a fairly mediocre healer, he actually fights well in close combat. This is the story of a support who's secretly a DPS, and where the entire conflict stems from the fact that he never told his old party he was a DPS.

(Source: Manga Mirai)