is originally a four tankōbon manga (inspired by the homonymous book) created by Go Nagai and Kunio Nagatani and published by Tokuma Shoten in 1990. It was later adapted into an OVA, , known in the United Kingdom as Kamasutra and in the United States as Kama Sutra and considered a hentai anime in the West. Plot Prof. Takeshi Aikawa is researching the location of an ancient Indian princess, Princess Surya of Gupta Empire. Prof. Aikawa's grandson, Ryu, becomes involved when the group of gangster attacking Ryu and his spoiled girlfriend Yukari and ransacks his grandfather's apartment in search for information about the princess until Ryu witnessed as he discovered the manuscript which actually was an ancient Indian sex manual called Kamasutra. Ryu goes to India to help his grandfather. There, he finds his grandfather's assistant, Shakti, who introduces him to learn the techniques which found in Kamasutra. Ryu and Shakti flight towards to Prof. Aikawa locations, however, they're kidnapped by the same gangsters who are working for an ancient Indian cult, the Naga Tribe, and soon takes them into the Palace of Naga. Ryu is sexually drained and physically debilitated while in captivity, but his grandfather and adventurous Indy Yakko manage to save them. Afterward, Prof. Aikawa's group goes to Khajuraho Temple to find a golden cup-like artifact called the Sex Grail, which is sealed inside of Rama's sculpture and with it they able to locate and retrieve the frozen princess Surya, who was resting at Himalayas, with using the grail to revive Surya from suspended animated state. Meanwhile, having failed at obtaining the grail, the person behind the attacks, the Old Master, dies and his son, Prince Rudra assumes the leadership for the tribe, and raping Jody, the Old Master's personal doctor in the process. He then personally kidnaps Surya with the intention of obtaining her love juice to be used with the grail. Rudra then tries to obtain the grail and succeeds by deceiving Ryu into an exchange of the princess for the grail. After obtaining the grail (and kidnapping Ryu in the process), he sends his henceman, Hige Godzilla to trick Yukari into raping Surya for them. Yukari does so and is also captured and is jailed along with Ryu before they are crushed and stuck by a wall trap. Yakko, however, is able to track them down and rescues them. While trying to escape, they're