Rohan Kishibe's Adventure, Part 1 (岸辺露伴の冒険 その① Kishibe Rohan no Bōken Sono 1), originally An Unmapped Road (地図にない道 Chizu ni Nai Michi) in the WSJ release, is the sixty-fifth chapter of Diamond is Unbreakable and the three hundred thirtieth chapter of the JoJo's Bizarre Adventure manga.
On his way to supplementary classes, Koichi meets Rohan who got out of the hospital. Unwilling to incur Josuke's wrath and having come to admire Koichi's personality, Rohan wants to make peace with him. Rohan then asks Koichi about the layout of the neighborhood, having lived here until he was four. Pointing at the street map nearby, he notes the existence of an unregistered street situated between the Owson convenience store and the Kisaragi Drug drugstore. As Koichi wonders how he never noticed that street, Rohan also points out that the mysterious street before them isn't indicated in the national map. Rohan wishes to investigate it with Koichi, and emotionally pressures the latter into following him. They visit the street, noticing nothing of note except the abandoned houses, but when they turn at the corner of the street, the exact same road is laid before them. Startled, Koichi tries to head back from where he came, only to meet Rohan again at the corner. As Rohan suspects that they are under attack from a Stand, and when Koichi sends Echoes up in the air, it bumps against an invisible barrier. A mysterious girl observes Rohan and Koichi from behind a street corner.