Fire in His Fingertips: A Flirty Fireman Ravishes Me with His Smoldering Gaze Vol. 4 - Kawano Tanishi - Bog

"When Souma returns from his training seminar, he expects to pick things up where he left them sizzling with Ryo, but with Ryo's ex, Rei, back in the picture, nothing is going according to plan. Rei is making Ryo's work life easier, and now they're doing research together, out on the town together, and pretending they're dating each other?! Even when Souma takes Ryo on a date, they end up with a crowd of three. Can Souma's trust in Ryo endure against his fears about Rei?"--