Enhancement of the fusion power multiplication factor, Q, has been investigated using a simple plasma model, in which the radial profiles of the plasma temperature and density or the fast-ion velocity distribution are the same as those observed in recent experiments. The break-even condition is relaxed by a peaked density profile, beam-plasma reactions, and the fast ions produced by ICRF heating at the second harmonic of deuterium in a D-T thermal plasma. The minimum nτT required for break-even has also been lowered. Furthermore, it is possible to enhance Q through local thermal instability near the plasma center using a simple transport simulation, in which the profile of the plasma density does not change during the simulation and only the thermal conduction loss is considered. Finally, the operational plasma parameters for JT-60 in the nτ vs. T diagram have been investigated.