Reading doujinshi for the Buddha’s sake.
Literally: harmony – light – same – dust
Alternately: An especially wise or talented person hiding their abilities (often through self-effacement) and living a common life among the common people. In a Buddhist context, the phrase describes how Buddhas and Bodhisattvas may hide their true nature and live among us in order to bring enlightenment to the masses.
Notes: Perhaps ironically given the Buddhist usage, this phrase comes to us from a foundational Taoist text: the 『老子』 (Japanese Roushi), i.e. the eponymous Laozi, a.k.a. the Tao Te Ching.
This is another compound of compounds: 和光 refers to the “softening” of light; 同塵 refers to something being matched to ordinary life, or to secular society.