I am currently researching Quark-Gluon Plasma (QGP), a high-temperature and high-density state of matter, through nuclear collision experiments. QGP is believed to have existed in the universe about 10⁻⁶–10⁻⁵ seconds after the Big Bang and is thought to persist inside neutron stars. Experimental results from gold and lead nucleus collisions at RHIC and LHC confirmed that QGP exhibits almost perfect fluid behavior, a property that cannot be explained by hadrons alone. I aim to resolve ambiguities arising from diverse theoretical models by identifying the initial state, as well as achieve a unified understanding of high-energy nuclear collisions. My ultimate goal is to uncover how the universe came to be.