Name meaning: Quiet Hero of the Peaceful Island (kanji reading: "peaceful island" and "serene man" respectively)
Birthday: January 28 (Aquarius)
Age: 24 (Anime & Manga) 25 (Novel)
Family: Kichirou Heiwajima (father), Namiko Heiwajima (mother), Kasuka Heiwajima (younger brother)
Height: 185 cm (6' 1")
Weight: 70 kg (154 lbs)
Hair color: brown when he was a kid. [current: golden yellow (blonde)]
Eye color: brown
Gang: Former member of Dollars.
Title: Strongest man in Ikebukuro.
Blood type: O
Hobby: basking in the sun
Occupation: bodyguard, Bartender (former)
Likes: running, books, relaxing, dairy products.
Dislikes: Izaya Orihara, violence, gambling
Favorite foods: milk, dairy products, desserts (sweet things in general)
Disliked foods: anything that's bitter, beer (his preferences are like a kid's, as far as taste is concerned)
Favorite quote: "I hate violence."

A man who is always seen to wear sunglasses and a bartender's suit. Although quiet and nondescript while not angered, he has a very short fuse and fights with incredible strength. Despite his simple and unrefined fighting skills, he is often considered the strongest fighter in the series. In the novels his power is described as the naturally unlimited form of human strength and likened to "adrenaline power" that can give people superhuman strength in times of emergency. In addition, Shizuo is capable of often superhuman parkour moves, a skill he obtained naturally from years of hunting down Izaya Orihara.

Shizuo works as a bodyguard for a debt collector in Ikebukuro and carries intense animosity towards Izaya. He has a younger brother, Kasuka, who is a top idol under the showbiz name of Hanejima Yūhei. He is also a long-time acquaintance of Celty.