Splatoon X has three DLC "adventures" that are like add-ons to Hero Mode. However, the player cannot actually access the DLC until they complete the main story mode, but they can buy it ahead of time so they won't have to later. They can still enter the map, but can't do any of the levels.
Completing the levels of adventure unlocks additional gear and weapons, similar to amiibo. Each level unlocks a new item, with each adventure containing about 5 levels (excluding the boss). The boss level will unlock another set of gear for the player, thus totaling two gear sets per adventure. The amount of weapons earned actually varies depending on what adventure it is.
Black and White
In the Black and White adventure, the Squid Sisters, Callie and Marie, mysteriously disappear from the studio, as noticed by several fans of the two. When Cuttlefish is informed, the player is told by the captain that he assigned the two, as agents, to find the remains of an old Inkling site from the Great Turf War located in Lobster Canyon. However, he has not heard from them since. The player and Nathan are assigned with finding the Squid Sisters and to safely escort them back to base.
In the Splatterai adventure, the player, Diana, Jason, and Jessica come across the mysterious Samurai Z, the Splatterai, once again. This time, the warrior tells the three where her home, a large temple, is located and invites them over for an Arena Dual match with one of them. After the offer is accepted, the three report the incident to the Cap'n, who tells them that he know Z's father but never got to see the Splatterai herself. He allows the player to head to the temple, but has them take Jason along as backup in case of a surprise ambush.