If you're looking for manga similar to BL First Crush Anthology: Five Seconds Before We Fall in Love, you might like these titles.
A short story about a conservative older office worker dating a 20 years younger kouhai.
After a night of heavy drinking with his competent and dependable coworker Kamiya, Kaji slowly begins to regain his consciousness... Only to find Kamiya straddled right on top of him, legs spread and wearing nothing but a half-unbuttoned shirt. When Kaji is finally able to muster the energy to get up, he immediately asks Kamiya to explain himself. His response? "Things went sour with my hook-up buddy, and I've been pent up lately. That's all." Since that day, for some reason, Kaji begins feeling drawn to Kamiya. This is the story of a recently divorced man, his coworker who's secretly promiscuous, and the attraction that forms between them, set in the world of the ever-competitive Toto First Bank's head office.
One day by chance, Ayumu learns his handsome, popular, and younger co-worker Takeru has a crush on someone. Ayumu encourages Takeru to make a move. But every time he does, he notices Takeru standing a little too close to him. Then again, why does his heart pound so much when Takeru stands near him? As Ayumu wonders how he feels about Takeru, Takeru finally makes a move...on Ayumu!
"That does it; my life is over now, for sure...!" -- Though he's good at his job, due to a stubborn streak and an overly serious attitude, office worker Sakura tends to take on too much. But he has a secret - after sunset on the weekends, he becomes "someone else." However, his junior coworker Arima sees him in this other form, and Sakura even gets stuck sharing his secret with the guy...!! Can straight-laced, earnest, bespectacled Sakura handle the onslaught from his blank-faced, pushy junior on top of all the rest of his stress?!
I found myself in a love hotel with my fellow male co-worker, and he started coming on to me. I had no idea he felt that way about me. I'm not exactly a model, after all...
Kosaka is a fashion design student and uses his classmate Nosaki Ritsu's butt as a model for his underwear clothing line.
Harehito and Oujirou are trash collectors. Harehito's hands can fix anything, like magic. When Oujirou's heart is broken, Harehito's hand, warm on his back, brings him to life. Once again, a request comes in to pick up a dormant boy. It's another sweltering day. Just like the day Harehito "collected" Oujirou as trash.
A shy and simple Sweets loving boy, Hodaka-kun and his secret hobby, making sweets. One day while he was eating his home-made Madeleines during Hanami, he found his company's idol Yamana collapsed at his door. Not knowing what to do, he gave him some water and Madeleines. Yamana loved the Madelaines Hodaka made so much that he started bothering him at the office the very next day. Hodaka, who started to feel cornered decided to invited Yamana to his house and....!?