In the title adduct, C15H10N4·2C10H10N2, the pyrimidine ring is nearly co-planar with the heteroatomic perimidine ring, as indicated dihedral angle between their mean planes of 3.21 (11)°. The di­aminona­phthalene mol­ecules are slightly twisted [dihedral angles = 4.2 (2) and 3.0 (2)°] because of the steric encumbrance of NH2 groups. The perimidine and di­aminona­phthalene mol­ecules are linked by N—H⋯N hydrogen bonds, forming an R 4 4(12) graph-set motif across an inversion center. In the crystal, alternating layers of the perimidine and di­aminona­phthalene mol­ecules are formed along [100]. In the perimidine layer, mol­ecules are π–π stacked along the c-axis direction with an inter­plane separation of approximately 3.4 Å.