Where does the ‘ji’ reading of 司 come from in 真司 (‘Shinji’) ?

Hello friends.
I have knowledge of both hiragana and katakana. I am starting my way into understanding and learning Kanji.

I was curious to understand the way that Japanese names are created , by seeing the process of choosing the readings between On’yomi and Kun’yomi, and I found out there are special pronunciations that are sometimes used for names only, called ‘nanori’ readings.

I was trying to find some examples of this and I stumbled upon the name 真司 (‘Shinji’).
While I can easily see that the 真 is read as しん / シン (shin) from the On’yomi reading, I can’t understand why 司 is read as じ / ジ (ji).
Online I’ve found various readings of 司, but no one is じ.
[For example, here](https://en.wiktionary.org/wiki/%E5%8F%B8#Readings)

Has it something to do with the pronunciations that could be too similar?
Example: “Shinshi”

皆さん、ありがとう!