This starts out with a interesting premise (former-life mortal enemies finding themselves in present-day romcom), and a strong start (skips over the "when will the truth come out!" part of any such story and skips straight to the "well what now" portion)...
...and then immediately devolves into a slightly sketchy gag romance manga in which their past identities are nearly completely irrelevant beyond the occasional gag.
What a waste of an intriguing setup!