Did he know the guys full name? If he didn’t then I’m pretty sure he wouldn’t have guessed his married brother was Haruki’s ex because I’m pretty sure there are a lot of Kota’s. If he didn’t know his full name at first then I’m pretty sure he wouldn’t have thought it was his own brother. That’s the last person someone would suspect, of all people.
You’d think they don’t look similar because of their hair and it’s a manga so almost all characters are gonna be drawn in the same style for the face, but other people/characters who saw both the brothers have said they look similar lol. I can understand the part about not being able to come to the conclusion that it’s your own married brother, since it’s hard to believe that. But people are talking about how he should at least pick up some sort of suspicion such as: “looks like you.” The person they talked about worked as an actor, so did his brother. And they share the same name. To share the same name as your brother and have a similar face, you’d at least suspect something was weird
Okay it is true I do think it’s kinda dumb how yuta didn’t piece it all together sooner. But the only thing I could think of is maybe he didn’t believe it was his brother since he might not have known that his brother had a relationship with a guy before getting married. But at the same time still dumb lol to have someone who looks and sounds like you and have the same name and not realize