There is a class picture of Yoshida (Teacher), Gintama, Katsura, Takasugi, Sakamoto with "Other" students when they were a child.
How come the "Other" students from the class picture did not appear when they grew up as an adult? (If I am not mistaken)
They most likely gave up on being a samurai and accepted the alien government when the war was lost and their teacher died or they were caught executed by the government for taking part in the war.
What I assume is they were probably killed in the war. You can see the picture below where there is an extra member (leftmost guy in the pic) in Gintoki's group that looks like Isao Kondo (Gorilla) but is not.
The identity of this guy is not known till date. So I assume he is one of those students who died in the war.
Yup. They either died during the war (most likely), or they gave up on their ways and accepted their alien overlords, unlike Gintoki, Katsura, and Takasugi. It's never truly specified in the Anime, but I'm going to assume that that's what happened.
