Summary form only given. J-aggregates of organic molecules are of great interest because of their ultrafast and large optical nonlinearity induced by the excitonic resonance and superradiance. Among J-aggregates composed of various aromatic or macrocyclic compounds, tetraphenylporphine tetrasulfonic acid (TPPS) J-aggregates are of special interest since they are model substances for aggregates of the light-harvesting antenna chlorophyll with a storage ring configuration in photosynthesis. The absorption spectrum of TPPS aggregates shows a relatively weak band in the red region and much stronger peaks in the blue-near ultraviolet, denoted as Q- and B-bands, respectively, composing a quasi-two-band Frenkel exciton system. In the present study, we observed for the first time dynamic intensity borrowing which results in the modulation of the Q-transition dipole moment.