Bruh c'mon they look nothing alike, Denjiro looks like Koshiro with a katana that looks similar to Wado Ichimonji, hell was Kyoshiro even born 41 years ago ?
Now I'll give my real opinion on this subject. Denjiro is not Koshiro.
First point: It's officially confirmed by Kuina's Vivre Card that Koshiro and Kuina were both born in East Blue. Also Oda said that two decades ago (20 years ago) a ship went from Wano to East Blue, and that someone we're familiar with is a descended from a person who was on that ship.
just by this information alone it's quite clear that Koshiro is not Denjiro, but he is son or grandson of whoever was on the ship that left Wano 20 years ago.
Second point: Denjiro
is an orphan, Koshiro
IS NOT.
Third point: Kyoshiro being different from Denjiro doesn't nullify that he's Denjiro. O-Tsuru who also has that "Edo period painting-style design" just like Kyoshiro, currently in the plot she looks different from the flashback of 41 years ago.
Fourth point: Even though Kyoshiro and Denjiro are different (just like current O-Tsuru and O-Tsuru from 41 years ago), Denjiro's silhouette from 20 years ago matches with Kyoshiro.
Fifth and last point: As Kejon said, although Kyoshiro is the owner of a brothe, his job is to be a money changer and we have seen that Denjiro is quite skilled at fooling people with money.
So yeah... Denjiro is Kyoshiro, Koshiro is not Denjiro.
@ZoroGang @Ice devil slayer @Zowo Take note my boys.