The Plant Appraiser (植物鑑定人 Shokubutsu Kanteinin) is the fifteenth story arc of JoJolion.
Years ago, Jobin is shown as a shy and withdrawn child, whose Rock Disease was beginning to take root; therefore, he had cracks along his body and suffered memory loss. Moreover, a bully was taking advantage of Jobin and tormented the boy. One day, the bully had Jobin steal his mother Kaato's underwear, but was discovered by a comrade. The bully tried to force Jobin to burn the comrade's house down, but Jobin refused. Almost burned himself, Jobin suddenly awoke Speed King and almost killed the bully. Kaato alone learned of it and used the opportunity. Instead of sacrificing herself, she told Jobin to have an equivalent exchange with the bully under the lone pine tree. Jobin then committed his first murder. Since then, Jobin has been a healthy and outgoing teenager. However, the bully's corpse was eventually found and the investigation led to Kaato's incarceration in the autumn of that same year, which she served for 15 years for Jobin's sake.
In the present day, Josuke and Yasuho take a bus to go find the Plant Appraiser. As Josuke realizes that Dolomite has been talking to something else than him, there is a new enemy who has taken interest in the new breed of Rokakaka. The bus is suddenly hijacked by the same plant appraiser he wants to meet, Rai Mamezuku, who demands that Josuke protects him first and foremost, as they are now under attack from an enemy Stand.
Rai Mamezuku, an analytical and unpleasant individual, eventually stops in a parking and invites Josuke and Yasuho to a chairlift, revealed to be his home, then cooks them a Romanoff cream. All the while, Rai and Josuke discuss. The enemy is a brand new organization which is surely powerful and desires the new fruit, as it allows people to defy death. Because of the enemy, Rai wants Josuke to make his protection the top priority. He is the only one who can find the Rokakaka and must be kept safe at any cost.
Rai wants to reach the 8th pole of his chairlift to retrieve something but a tree sneaks on the group and releases a swarm of cube-like Stands who can dissolve flesh and create holes on the body. Josuke instinctively protects Yasuho, which costs Rai his hand. Miffed, Rai throws Yasuho down the chairlift to expose her to the enemy attack and observe their power. Soon enough, Yasuho is attacked by in fact two Rock Humans. One of them human-like and possessing the cube Stands, the other having the form of a threaded vehicle who moves underground and in whom is encased the first foe.
- 064 (911). The Plant Appraiser, Part 1
- 065 (912). The Plant Appraiser, Part 2
- 066 (913). The Plant Appraiser, Part 3
- 067 (914). The Plant Appraiser, Part 4