Now that the store security guard on floor 3 of Luigi's Mansion 3 is out of business, we will be able to explore the second floor, the mezzanine. This should remind you of something, since we are above the main hall. On this new floor, use the suction shot over the door blocked by the prohibition sign and enter the heart of the mezzanine.
Run to the end of the corridor and walk through the huge golden door to the dining room where a nice bunch of ghosts armed with food await you.
Eliminate them effectively: once you catch one in the Vacuum, make it crush its spectral buddies who would try to get a little too close. This method works for all the gang fights you will have to perform during the game, projection is clearly your best weapon, so learn as soon as possible to optimize its use. Then enter the kitchen to face the boss on the first floor.
Floor 2, Mezzanine: Boss Chef Soufflé
First, take Gooigi out and then suck in the thick cloud of smoke that covers the room to reveal the cook boss. The guy's pretty upset, so stay at a safe distance at all times. To defeat him, start by dazzling him, which will force him to protect himself with his frying pan. As usual, when you see a big circle in the game, bim, little suction cup: then pull on the pan to disarm it. Krem will then be at your mercy: reuse your torch and vacuum like you never vacuumed before. In two or three cycles, you should smoke it like a salmon without too many problems.
Well, now that the boss is finished, you can recover... Well, no, a rat just swallowed the elevator button! Follow him to the dining room, this smart guy went into a hole under the buffet. To get him out of hiding, take one of the pieces of cheese and put it face to the hole. Step back a little, then come back to see that the rodent is eating: no pity, flash him a good punch, then watch the elevator button get swallowed again by one of his colleagues.
Go ahead, another chase, chase down that new rat, then enter the room just to the right of the front door of the landing. In this game room, you will face new orange enemies: they hide in unlikely places, so you will have to interact with objects that move on their own to hunt them down and suck them in. Once the threat has been removed, destroy the central locker at the back of the room, as usual, with a well-placed suction cup. This will flush out the rat, which will go for the occasion to visit the toilet.
Back in the corridor, take the first one on the right, then pass the second door: pull a suction cup on the plate to transfer the ventilation protection to the left wall. Pass Gooigi through the pipe, then destroy the door of the center to unveil a beautiful band of rogue rats. Exterminate all this, then grab (finally) the button for floor 4, where your first real boss fight awaits you.