Apparently, Disillusioned Adventurers Will Save the World, Vol. 4 (manga)

Four jaded adventurers and now a sentient, transforming sword? Bond the magic sword was abandoned by the ancient civilization that built them after they were no longer useful, so he’s a perfect fit for the party! The gang’s getting bigger and stronger, so a little relaxation can’t hurt...but who’s that familiar face at the other table? Nick’s conniving ex-girlfriend...!?