Midtown is a dungeon in Shin Megami Tensei IV.
Most likely the Midtown Tower, which is found in the Midtown Development. It is the tallest building in Tokyo and is in the Roppongi and Minato regions. The building has 54 floors above ground and five below. Floors 7 through 44 are for commercial offices for different businesses, floor 45 through 53 is for a hotel, and the 54th is for keeping building components and other materials for maintenance of the building.
A building under the control of the Ashura-kai and guarded by the National Defense Divinity Tenkai, who can be seen meditating in front of it during the game. Learning from Fujiwara that a path to Reverse Hills can be found here, they will be able to traverse the building once they beat Tenkai. On the first floor Demons can be talked to in the rooms on the bottom floor alongside a Ashura-kai member, talking about Reds, Tayama, new workers, and Mastema.
A barrier is in place to prevent anyone from going to the underground floors. A elevator on the first floor leads to the 33rd floor, which has a elevator that goes up to the 43rd floor, and the elevator from that floor leads to the 54th floor. A barrier is also found on this floor and Mastema can be found here. After talking to Mastema the barriers will be removed and the elevator on the 54th floor can take one down to the first floor.
Fujiwara mentions the Japanese Defense Agency used to be in Midtown and that if it was chosen by Tayama as some kind of poetic justice, then he must have a weird sense of humor.