  The quasi-two-dimensional organic semiconductor \alpha-(BEDT-TTF)2I3
[BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] has an anisotropic linear
dispersion with a zero energy gap near the Fermi level. Owing to the vanishing
density of states at the Fermi level, the Coulomb interaction is unscreened in
this material. We theoretically study the effect of the long-range Coulomb
interaction and the low-energy/long-wavelength behavior of \alpha-(BEDT-TTF)2I3
using the renormalization group analysis. The nearly logarithmic enhancement of
the velocity reshapes tilted Dirac cones, and changes the low-temperature
behavior. We also show the theoretical calculation for the site-selective spin
susceptibility, which can be measured in an NMR experiment.
