Ryota Uemura murdered in Japan
Ryota Uemura murdered in JapanGetty

The killer of a teenager in Japan may have been inspired by gruesome videos of gory executions by Islamic State (IS) terrorists.

An investigation is underway after the body of Ryota Uemura was hauled from the River Tama in Kawasaki.

On his neck were a series of knife wounds which officers suspect were signs of a bid to decapitate Uemura, in the style of Islamic State executions.

Japanese society was shocked recently by the high profile murders of two men from the country, who were held hostage by IS fanatics.

Haruna Yukawa and Kenji Goto were slain earlier this year - with at least of their beheadings carried out by the terror group's most infamous killer Jihadi John.

"Some investigators suspect (the criminals) watched internet videos showing the execution of hostages by Islamic State fighters and sought to mimic them," reported news magazine, Shukan Shincho.

One teenager was arrested and held by police investigating the murder. His name was not revealed because of his young age. Arrest warrants for two more teenage suspects have been issued.