Hiroto Shijima

Hiroto Shijima (四十万博人 Shijima Hiroto), is introduced as the second in command of a drug cartel that primarily deals with a very unstable and powerful drug called Heaven's Slave. For simplicity's sake the group is referred to here as "Heaven's Slave" as well.

He is one of two major antagonists introduced in volume 09 of the light novel series along with Mimizu.

Dragon Zombie Arc
During his college years, Hiroto was part of an "Experimental Legal Drug" club started by Izaya and Nakura.

Hiroto proved to be very proficient at mixing and experimenting with different substances. This would further cement his role as the eventual leader of the Heaven's Slave group.

After graduation, Hiroto formed Heaven's Slave. He began experimentation to create a new drug. The drug was in limited distribution since about five years before the start of the series. Said drug was even responsible for Anri Sonohara's father's drug addiction. To protect himself from incrimination, Hiroto decided to frame Nakura as the leader of Heaven's Slave. Hiroto played the role of an obedient second in command. He used one of Nakura's aliases, "Kumoi", as the name of the "leader" and did what he could to make "Kumoi-san" seem real. Hiroto went as far as inflicting injuries on himself when his plans weren't successful to make it seem like "Kumoi-san" was punishing him.

By the start of Volume 09, Heaven's Slave had become more widely distributed and Hiroto's cartel was starting to encroach on the Awakusu's territory.

Wanting to avoid an all out gang war on two fronts, Shiki hires Izaya Orihara to dig up what he can about Heaven's Slave and Amphisbaena. Izaya leaves a laptop with most of the information he collected on both groups with Celty. Hiroto and his men were spying on both of them at the time and kept tabs on Celty the entire night. The next day, when Celty was distracted, Hiroto's men steal the laptop and take it back to their hideout to analyze it. Hiroto finds Amphisbaena's hideout, the same place where they were keeping Izaya for interrogation.

Hiroto sends some of his men to tail Mairu Orihara. At the same time, he and a small entourage barge into Amphisbaena's hideout. Hiroto demands that Mimizu hand Izaya over. Hiroto habors the intent of killing Izaya for all that he knew. The two argue over what to do with Izaya when Mimizu gets a call from someone claiming to be the "real Izaya." Both Hiroto and Mimizu are dismissive at first. They become panicked when "Izaya" hints at the person under the bag being not only the wrong man but actually either Mimizu's or Hiroto's boss. Mimizu loosens the restraints when another group of people barge into the room.

The man Amphisbaena had tied up begins laughing and reveals himself to be Izaya himself. The person on the phone was Ran Izumii. Izaya goes on to explain that he allowed himself to get kidnapped as a means to lure both groups into a corner. After dispatching Amphisbaena and Hiroto's henchmen, Izaya coerces Hiroto into joining forces with him. Izaya claims that Hiroto would have access to the Dollars information network and be able avoid all out conflict with the Awakusu. Hiroto begins to threaten Mairu but Izaya states that he hired Celty to protect his sisters in case of this eventuality.

Kadota's Coma Arc
Hiroto is on the run after having been cornered by Izaya. He heads home. Hiroto's father and grandfather are implied to be powerful and rich, especially his grandfather, who knows a politician. He plans to use his family to take revenge on Izaya. However, when he gets home, Yodogiri and his secretary, Kujiragi, are at his house speaking to his father and grandfather.

Yodogiri intimidates both Hiroto's father and grandfather, so they attempt to curry favor with him. Hiroto's grandfather says he is aware of Hiroto's crimes and will deal with the Awakusu. This raises Hiroto's hopes, only to crush them when he is told to obey Yodogiri and not let Yodogiri down. Yodogiri expresses his interest in the Dollars, claiming to have been interested in it for a long time.

Hiroto's grandfather fended off the Awakusu with three hundred million yen, funded by Yodogiri. In return had to affiliate the family to the yakuza. He was unable to convince the Awakusu to overlook Yodogiri.

During the Dollar's "cleansing", Hiroto approaches Mikado as a friendly Dollars member looking to help. This is presumably under the request of Yodogiri. Mikado is unaware of Hiroto's past and his bitter desire to bring as many people as he can down with him.

Durarara!! SH
He makes an appearance in the end of the second light novel along with Mimizu.