Well except the Japanese do not like half Japanese. The whole society is xenophobic. According to Japanese law a mother can not pass on citizenship either. They haven't joined the 21st century yet.
Hafu are extremely popular in Japan now. Actors, models, singers, TV personalities, and entertainers of all sorts who hare hafu are all the rage.
A very large number of Japanese travel abroad for work or pleasure. Foreign foods, entertainment, style, goods, etc. are all very popular and consumed by the general public much more so than is the case in the US, for example.
As has been noted, a mother CAN and does pass on citizenship to her children.
Japan has not only joined the 21st century, they are leading it in certain areas.
In other words, Retired was wrong on all counts.