Self-assembly and fibrous structure formation based on pyridazine-3,6-diol-annulated tetrathiafulvalene derivative were investigated. Although the molecules formed a trimeric assembly with complementary hydrogen bonds in solution, the addition of water produced micrometer fibrous structures. On the other hand, mixing of diamines (NH2-R-NH2) promoted reorganization of the self-assembly, and various nanoobjects were formed.