A straightforward green synthesis of 4-methyl-1,2,5,6-tetraazafluoranthen-3(2H)-one 6 is reported from ninhydrin 1 via condensation with ethyl acetoacetate, followed by cyclization with hydrazine hydrate in water as a benign solvent. Tetraazafluoranthen-3-thione 7 was obtained using Lawesson's reagent. N-alkylated tetraazafluoranthen-3-one 8−12 and Salkylated analogues 13−15 were synthesized via alkylation. The investigation of the unique reactivity of 4-methyl-1,2,5,6-tetraazafluoranthen-3(2H)-one/ thione toward the alkylation and aza-Michael additions was explored.