Tateishi and Mitsuya are dating. There's just one issue: They work at the same company, and have to keep their relationship a secret. Since it's a romcom, there's no need to say that they're hilariously bad at hiding their relationship, and often act quite suspicious. At work, Mitsuya is mostly cold and insulting, which is the exact opposite to her real self. When they are alone, she's completely lovey-dovey instead. The manga has a nice balance of both, showing some of their interaction at work, but then also sprinkling a bunch of cuteness in between. Their romance does have some decent progress and also some moremature situations between them, so you will see more than just some awkward hand holding.

Also, I really like the art, it just looks adorable.