Of the End features the all new "Make a Partner" system, which follows in the footsteps of the "Let's Make a Fighter" and "Let's Make a Number 1 Hostess" systems of past Yakuza games.
After clearing substories, you'll be able to make some characters turn into partners. You can raise these characters through Gary's Boot Camp, making them build experience and earn skills through Field Combat and Shooting Range.
Partner characters include familiar characters from past Yakuza games (shown here, Makoto Date). It also looks like the hostesses will serve as partner characters. You'll get different partner characters depending on the current main character, but after you advance in the story, the partner characters will be sharable between the main characters.
This appears to be a random dungeon -- at least, according to the few people who've returned form it, its form changes each time you enter. Progress through to the bottom floor of Kamurocho Underground, and you'll encounter a boss. In exchange for your effort, you'll gain a good amount of experience and items. It also looks like by making it to the bottom floor you'll close in on the reason behind a dungeon being in Kamurocho in the first place.
Akiyama, one of the game's four main characters, finds himself trapped with his secretary Hana inside the sealed off zombie-infested area of Kamurocho. As he and Hana attempt escape, they meet Tojo Clan member Tomoaki Nagahama (that's him looking into the manhole).
In two of these shots, we see Akiyama at the wall that the Self Defense Force has erected to keep the zombie infestation out. The area inside the wall will expand as the game progresses.