Wheelchair users would have no concerns about using restrooms as there are many multipurpose restrooms in Narita Airport. My best recommendation is to use the multipurpose restroom at the International Arrival Lobby on the 1st floor of Terminal 2. It is spacious and has enough equipment such as bidet functions. I found two multipurpose restrooms in the ladies’ room at the restaurant and shopping area (the Airport Mall) on the 4th floor of Terminal 2. However, the multipurpose restrooms at the International Departure Lobby on the 3rd floor of Terminal 2 are still somewhat old-style. I would like to expect them to be refurbished in the future. The multipurpose restrooms in Terminal 3 are clean and well-equipped because it is the newest building. I can say the multipurpose restrooms in Terminal 1 are also easy to use. It might be challenging for wheelchair users to use a lavatory during a flight. You would be relieved to use the multipurpose restrooms in Narita Airport as you leave or arrive at Japan.