The fourth installment of the Angel Guts series, Tenshi no harawata: Akai inga (or Angel Guts: Red Porno in English) continues the franchise's signature blend of steamy erotica and brutal violence. Released in 1981, this "pink film" from director Toshiharu Ikeda is an unapologetic descent into the seedy underbelly of Japan, centered on the character of Nami, a department store employee.

Nami leads a rather solitary life, her sexual desires often going unfulfilled. However, when a colleague persuades her to fill in for a porno modeling job, her world takes a turn for the bizarre. Her appearance in the magazine, aptly titled Red Porno, sets off a chain of events that are as salacious as they are shocking.

Ikeda's film embraces the "pink film" genre, with sex being the driving force behind the narrative. However, it's the exploration of Nami's growing obsession with rape that gives the film its edge. A scene in which she visits another rape victim and takes pictures, only to be cautioned by a man from a sex club who claims to work for a porno publisher, is particularly memorable. It captures the film's ability to blend titillation with a darker, more disturbing undercurrent.

That being said, Angel Guts: Red Porno often feels like a retread of the ground covered by its predecessors. With a runtime of just over an hour, the film struggles to justify its existence beyond its shock value. The plot is thin, and the characters are largely one-dimensional, serving only to propel the story from one sexual or violent set piece to the next.

Where the film does show some spark is in its stylistic choices. The use of vivid colors and shadow, coupled with the grainy film stock, gives the film a distinct look that enhances the seedy atmosphere.

Overall, Angel Guts: Red Porno will appeal to fans of the pink film genre or those seeking out the more obscure corners of world cinema. However, with its reliance on shock value and a rather formulaic approach to storytelling, it fails to leave a lasting impression.

While the film doesn't quite reach the heights of erotic thriller greatness, it does provide a fascinating glimpse into a very specific subgenre of Japanese cinema, one that is unapologetically raw and provocative.