In 1959, Kuroda Kan'ichi was expelled from the RCL in the wake of a scandal in which he tried to sell compromising information about the JCP to the Tokyo Metropolitan Police Department (MPD).

Therefore, Kuroda, along with his right-hand man Nobuyoshi Honda, founded their own version of the RCL, with the appellation "National Committee" added to the name, and took many of their followers with them to create the RCL-NC.

[4] Finally in 1963, the parent organization RCL-NC split in two as the result of a disagreement between Kuroda and Honda over whether to pursue socialist revolution in alliance with others, or to focus on strengthening and expanding a single revolutionary organization, with the resultant split of Marugakudō into the "Central Core Faction" (Chūkaku-ha), which was led by Honda and favored allying with others, and the "Revolutionary Marxist Faction" (abbreviated Kakumaru-ha), which staunchly adhered to Kuroda's insistence on going it alone.

[5] The two groups had frequent violent conflicts and, by the mid-1970s, these were resulting in several deaths per year—16 in 1975 alone,[6] including Kakumaru-ha's assassination of Chūkaku-ha's leader Honda Nobuyasu.

In 1998, police seized thousands of recordings of their conversations made by Faction members, which a spokesperson claimed had been "necessary to protect the organisation.