Kiss wa 10-nen Tatte kara

Riko Sasamoto has treasured the bittersweet memories of her unrequited love from high school. But 10 years later, she is reunited with her crush Shirai-kun at work, and they start dating! Their first date, the first kiss, and the first time... Riko's heart is on the verge of exploding from all the "firsts" that come one after another!

(Source: Palcy, translated)