Rescue Johnny Gat
Once you're inside Johnny's simulation, you'll have to proceed playing as a sidescroller. The controls are simple and the stage is very straightforward. Beat all enemies along the way and the stage will be complete. Breeze through the first floor of the second stage and pick up food items along the way to restore your health. In the next floor, you'll have to face the boss. Take him out to complete the stage.
Continue through the third stage with minimal effort. Proceed until you reach Aisha's house. Once inside you have to face Junichi. Just attack him normally and he'll transform into Super Junichi. When you see a crosshair appear, get away from that location since Junichi will be landing there. Other than that, this is practically the same battle as earlier.
In the next section, you'll be piloting the power armor again. This is a very straightforward path again. Just follow the markers until you reach a processing tunnel. There, more marauders will engage you from platform to platform. Just get them to aim at you then quickly move behind them and target their weakness at the back. Continue until you reach a large room that will be locked by a force field. Go to the upper platforms and take out enemies as you wait for the force field to be taken down. Once the path's open, just ignore the other enemies and get inside. Kill a few more obstacles along the way and watch the next scene. Quest complete.
Dash Shield and Death from Above skills will also become available. Johnny Gat will also become part of the crew and will also become available as a homie. New Side Quests will become available as well.