Hadron interactions and exotic hadrons from lattice QCD

One of the interesting subjects in hadron physics is to look for the multiquark configurations. One of candidates is the H-dibaryon (udsuds), and the possibility of the bound H-dibaryon has been recently studied from lattice QCD. We also extend the HAL QCD method to define potentials on the lattice between baryons to meson-meson systems including charm quarks to search for the bound tetraquark Tcc (ud $\bar{c}$ $\bar{c}$) and Tcs (ud $\bar{c}$ $\bar{s}$). In the presentation, after reviewing the HAL QCD method, we report the results on the H-dibaryon, the tetraquark Tcc (ud $\bar{c}$ $\bar{c}$) and Tcs (ud $\bar{c}$ $\bar{s}$), where we have employed the relativistic heavy quark action to treat the charm quark dynamics with pion masses, m$_{\pi} =$ 410, 570, 700 MeV.