-characters in both work in an ad agency
-ML is FL's boss
-ML is cold/strict to FL but secretly caring
-ML essentially mentors FL
-FL is more focused on work than love
-ex-boyfriend (who also works in ads) comes back and wants to date again
-similar side characters
-romance comedy

-Long time Friends to Lovers
-Slow burn romance
-ML falls first
-ML is a photographer
-FL likes someone else initially
-Similar relationship dynamic of the two leads

Although different in genres and setting (Blue Birthday is a high school based romance, 365 is more pure thriller), they both have a similar premise of going back in time to save a loved one. They also have some similar twists (although I wont say more so as not to spoil). Blue Birthday is more light-hearted while 365 is more dark and suspenseful, but if you're looking for a similar set-up and don't mind the tone changes, give it a go!