This is a classic donburi (bowl of rice topped with food).
Oyako means parent (oya) and child (ko). The name comes from the main proteins in the dish: chicken (the parent) and egg (the child). Some shops use this name to market other ingredients, such as duck (kamo no oyakodon). In Kansai, the west of Japan, some shops refer to this dish as “cousin (itoko) don”. There is even a seafood version of the parent and child donburi, including cooked, raw, or flaked salmon with salmon roe, called “seafood (kaisen) don”.
The origin of oyakodon dates back to 1887, when a small Tokyo restaurant called Tamahide is said to have first served it. The restaurant, located in the neighbourhood of Tokyo known as Ningyocho, is still open to this day, and is very popular for its historical oyakodon.
Heat the frying pan and add the chicken, onion and seasoning ingredients.
Bring to a boil, then add some chopped mitsuba and the mixed egg. If you like your egg more runny, add only 3/4 of the egg mix at this point.
Return to a simmer (and add the rest of the egg mix), then turn off the heat and dish it over a bowl of steamed rice.