Harlem in Town
You've got half the crew so far but you also need someone special that will play a crucial role in keeping your team alive. Diana whom have helped you in the first three chapters will now decide whether to join the team or not. As a prologue she has about a year to live and you invited her up to the theatre to see the performance.
Damsel in distress
Depending on who loves you the most, on of your crew and Rosita goes over to see Diana. Along the way, Rosita catches a bird which lead to an event which goes horribly wrong. Diana doesn't like dead birds! This causes Rosita to let go of the bird. Because of that incident, your crew can't approach Diana again. So on to the next task.
New York and Harlem
You should decide to let Diana see the musical performance. Afterwards you'll be taking her around town in a wheelchair. Along the way, you'll meet the girls that appears from their location. Finish with your errands before you go to the theatre.
Birds of fate
It's worth mentioning that you and your team is taking care of the bird that's injured and you have time to go out and investigate at the dead of night. When you're done searching for things to do, you go home to sleep. But one of the girls got attacked by a bird and realise what's going on: The bug in the bird is what irritates them to attack people. Take a picture and bring it to the theatre.
Change of heart
Your angry at this point because of the inaction Diana takes. Eventually, the bird that was injured takes flight to Diana's place to save her from the bugs. At this point, she first uses her pneuma to stop the people killing the birds before going on the STAR to take action.
To be or not to be
At this point the battles are getting harder. The spores on the top regenerate poisonous plants and within a few turns goes in and if all are sucked in, the games over. Also the robot minions regenerate as well. Follow this instructions: You and Subaru take to the air to take care of the spores as fast as you can while Diana, Cheiron and Rosita take care of the plant spores and the regenerating robot minions as much as they can and remember to keep the defence up.
Perhaps what's intriguing is her special power move is to heal your crew completely so use this wisely and make sure your really close to the group in order to work. Even the healing works well. The final boss is not that hard. After the pneuma is cleared by the birds, get your crew to take care of the arms, head and the robot minions attacking you. Then take down the gateways that sometimes take turns spinning like a wheel of fortune so try to attack the pneuma in one of the windows that tries to protect it and it's all over.
Congratulations! You've got five people in your team so far. On the next chapter, you have to deal with Subaru and Gemini on the 6th chapter. Don't expect it to be easy at this point but only in battle.