Regulatory subunit of the condensin-2 complex, a complex that seems to provide chromosomes with an additional level of organization and rigidity and in establishing mitotic chromosome architecture. Component of the condensin-2 complex, which contains the smc2 and smc4 heterodimer, and three non SMC subunits, ncapg2, ncaph2 and ncapd3 that probably regulate the complex. Belongs to the CND2 H2 (condensin-2 subunit 2) family.