Editor's note: This is part of Polygon's guide to September in Persona 5. If you're looking for more, be sure to check that out.
Tomorrow we leave for Hawaii, but today, we journey into Mementos. First, answer your school question with "Chronostasis," and then head into Mementos. You should have five missions before you begin: "Who’s Muscling in Yongen-Jaya," "Winner’s Don’t Use Cheats," "We Aren’t Just Your Slaves," "Who’s Been Assaulting People" and "Calling for Justice for Cats."
Jump into Mementos and Head down to Area 1 of the Path of Kaitul. Here, you will happen across Shadow Tsuboi, who has been a real jerk to cats lately. They are weak to Bless.
Next, move on to Area 5 of the Path of Kaitul, where you will encounter Shadow Naguri. This fight is fairly easy, so conserve your SP and use Physical Skill against them. Keep in mind that you critical hits will knock bosses down regardless of weaknesses.
Now, head down to Area 8 of the Path of Kaitul. Down here you will find Shadow Kishi, who is also weak to Bless. This enemy uses Brainwash, a nasty ailment that turns your own teammates against you. Make sure that you use your magic or items to cleanse allies as soon as possible.
After you have felled Kishi, head down to Area 10 of the Path of Kaitul. Walk up and face Shadow Jochi. Jochi is weak to Electricity skills, so make sure you rotate Ryuji in.
Once Jochi has learned the errors of their ways, you will be able to open the door and move deeper into Mementos. Head down the escalator and discover the Path of Akzeriyyuth. Travel down to Area 5 in order to find Shadow Nejima, the infamous cheater.
Nejima will not go down like all of the bosses before him. In fact, he won’t even take damage at all. Swing at him a few times (make sure to keep an eye on Joker’s health, just in case anything goes bad), and eventually you will be forced to retreat for now.
Time to leave Mementos. Head home and talk to Sojira and Futaba about leaving for Hawaii. Morgana will act very upset at you and refuse to talk much. Whatever. We will deal with him a little later. Time to go to sleep.