The Shortser

(from ebookjapan):

This short gag work by Leiji Matsumoto, a master of the SF manga world, depicts the free lifestyle of a middle-aged man who wears nightwear all year round. Shigeru Kusaba, a young man who has moved to Tokyo after getting a job, encounters a middle-aged man, Shuzo Sawatari, who is wearing pants at the apartment his company has assigned him.

The next day, Kusaba goes to work for the first time and is reunited with Sawatari, who is also wearing nightwear in the company...!?