Kepler-398 is an orange K-type dwarf (about 0.72 solar masses, 4,557 K, 0.67 solar radii), 177 light-years from Earth. Kepler-398 b is a planet with 0.9 Earth radii, with an orbital period of 4.1 days, at 0.044 AU from its star, discovered in 2014 via transit. Kepler-398 c is a planet with 1.0 Earth radii, with an orbital period of 11.4 days, at 0.087 AU from its star, discovered in 2014 via transit. Kepler-398 d is a planet with 0.9 Earth radii, with an orbital period of 6.8 days, discovered in 2016 via transit.