Gintama Episode 146 -

Gintama episode 146, "The Taste of Beer After a Day's Work is Something Special," focuses on the final, intense fight against Hosen, concluding the Yoshiwara in Flames arc with the liberation of the underground city. The latter portion of the episode shows the aftermath, featuring the residents rebuilding and the main characters enjoying a drink together.

You can watch the climax and closing moments of this arc here: Gintama Episode 146