This picture depicts a straight-up naked Jun Sawada, alongside three of his most notable roles, from left to right:

-SECOND PICTURE: Jun Sawada as Mr. Kurohata from Mitsuri no Kuma (1999-2007)-

Kanehiko Kurohata (黒畑金彦), or simply Mr. Kurohata, is the owner of the Kurohata Apartments where Goroh (played by Masayuki Tamura), Panta (played by the late Andy Liao, 1950-2007) and Polar (played by Nobuichi Tsukimoto) live.
Mr. Kurohata usually threatens to get violent with the three protagonist bears if they haven't paid him the rent for a month or more.
Mr. Kurohata is very greedy and doesn't care about anything outside money and his family, especially in the first season (1999-2001), but as of a 2000 episode where his father Ishio dies, he has also shown to have a heart at times, such as when he starts an unsuccessful relationship with idol teacher Minami Hayakawa (played by Tomoe Hirazaki) which ends abruptly when Mr. Kurohata learns about Minami being engaged to someone else.
When Jun Sawada was diagnosed with stomach cancer and forbidden to smoke ever again 2016, Maiko Suzuki, creator and director of the series, was given no choice but to retire the Mr. Kurohata character from the series, with the excuse that he had kicked the three bears out of the apartment.

-THIRD PICTURE: Jun Sawada as Makuo Oozeki (Koisuru Sumo, 2014)-

Makuo Oozeki (大関幕雄) is a sumo wrestling trainee with a crush on a school girl called Junno Morihata (森畑純乃, played by Aiko Miyanishi).
During his training sessions, Makuo can't help but think about Junno and can hardly speak to her out of nervousness.
Things start to get a little fishy near the end of the series, when Makuo Oozeki finds out that Junno is now on a relationship with a boy from her school (played by Hidetaro Sugikawa) and eventually they get married at the end of the 15-episode series, with Makuo accepting his defeat, albeit in tears.

-FOURTH PICTURE: Jun Sawada as Shingo Onaka (Itsuri no Bakagumi, 2011-2018)-

Shingo Onaka is a heavyweight bear who holds no second thought on worshipping his fat body and gaining more weight, even when his friends try to convince him that it can worsen his health and raise his chance of dying.
Shingo's personality is largely based on that of Jun Sawada in his highschool years, with Shingo aspiring to become a champion sumo wrestler and falling in love with a girl which prompts him to start a diet in a 2013 episode, which is ultimately cut short after he finds out she already has a boyfriend.

Jun Sawada died on October 1st, 2018 at 66 years old. R.I.P.