After the Big Three, the remaining samurai are a tad more one-note. Their unique traits are summed up more or less as soon as we meet them, and their arcs stay pretty limited in the face of the rest of the film's goings-on. Foremost among them is Shichiroji, who has the distinction of living through the closing credits, and more or less serves as Kambei's counselor.
He's defined less by his own traits than by his association with Kambei. They both had the same lord and they both survived the battle that presumably killed him, though neither of them knew it until Kambei's finds him while looking for samurai to recruit. It's a pleasant meeting, all the more because Shichiroji knows exactly what his old friend has been through. They totally get where the other one is coming from, and in a situation like this, that's worth more than its weight in gold. "When the castle finally burned down and then almost fell on me," he says. "I thought I was gone."
That makes him pretty much a mirror of Kambei in a lot of ways. He's a little sunnier and smiles a little more easily, but he doesn't hesitate when he hears the details of the plan. A desperate battle? Long odds? Nothing but a three bowls of cold rice and some grudging tolerance as a reward? "High five me bro, 'cause I am IN!"
His presence provides Kambei with a cold comfort, as well as a friend to confide in. They've got each other's back, and with the earnest enthusiasm of Katsushiro to back them up, they make for a pretty tough core of this scruffy band of misfits.
And Shichiroji suffers the same fate as his leader: he's alive at the end while his comrades have mostly died. It's the second time they've gone through that particular scenario, and like Kambei, Shichiroji feels every inch of it. The good news is that their shared burden binds them together and they head off as a duo. Whatever happens next, they won't be facing it alone. The bad news is that the burdens don't get any easier, and while Shichiroji's a little slower on the uptake than Kambei, he feels all of it as we leave them staring at their comrade's graves. Survival is no victory here, and companionship means mostly sharing those sorrows, not diminishing them in any way.