Regarding the red vinegar of "Mizikan", which represents "Yambuki", in the book written by Kiyosaburo Koizumi, the fourth generation of Edomae Sushi "Yubei Sushi", in Meiji 43, he wrote that "the vinegar used is limited to Oshu." Handa's Yamabuki" is such a sentence.
This non-sweet vinegared rice with popular database strong umami red vinegar mixed with salt has always been loved by Edoko, and has been the standard of vinegared rice in Edomae sushi since the Meiji, Taisho, and early Showa eras. It was not until after the "yellow-to-rice incident" in 1952 that we mentioned earlier that white vinegar was used. Compared with red vinegar, white vinegar has a stronger sour taste. If you use it directly, the taste may be unbearable, so many shops add sugar to adjust the taste. Also because of this, the taste of vinegared rice is sweetened.
In addition, during the period of high economic growth in Japan, the number of people coming to Tokyo from all over Japan has increased, and many high-end sushi restaurants have also added sugar to vinegared rice. And because sugar has the effect of retaining water, it can prevent the vinegared rice from becoming dry and hard, which is especially important for take-out or take-out sushi.