Complex sentence: There are also death gods called shinigami, which are closer to the Western tradition of the Grim Reaper; while common in modern Japanese arts and fiction, they were essentially absent in traditional mythology.
Split into simpler sentences: There are also death gods called shinigami, which are closer to the Western tradition of the Grim Reaper. Shinigami (often plural) are common in modern Japanese arts and fiction and essentially absent from traditional mythology.