Bride in 365 Days: Unexpected Marriage Proposal

"Marry me. In one year." Getting proposed to by a man who she thought was her best friend?! Hinano Ito, age 29, was pursuing a relationship-free life age 29, since an event traumatized her 5 years ago. Riku Yamazaki works with her at a sports company, and is a track and field record holder from college and is thriving at work. They are co-workers and best friends, and Hinano sometimes even spends the night at Riku's place when she misses the last train after a long day of work. But one day, Riku suddenly proposes marriage out of nowhere! Riku is now aggressively approaching her... and then they're put into a situation where they have to sleep in the same bed... what happens when a best friend suddenly turns into a boyfriend?!

https://www.cmoa.jp/title/271081/