Why is Seiji Sawada's Ponglei code name 27?

Sawada Tsunayoshi Romangi: Sawada Tsunayoshi.

Source of code 27: tsuna, tsu(2, tsu is the Japanese pronunciation of the English word two) na(7, pronounced nana in Japanese) or the number 27 on the glove in an inanimate state, which was also written on Johnny Er-gei's earphone in the future. The number "27" is usually printed on clothes, so it is 27)