Valid Information .

Goro is the only one who has the ability to protect Shoto.

That is not because he is a serial killer; rather, it is because Nakamura Goro is a brand within himself.

Even outside of Japan, the Nakamura family is very powerful, which means that The Tanaka Family cannot harm him foolishly. Goro is also the Heir to The Nakamura conglomerate and Sole heir to the  Lenoa Corporation. To put it short, Goro has unlimited Money, his name owns multiple shares in a lot of businesses and chain businesses linked to The Nakamura Family and Lenoa Family. Both families are made from old money and upon the Marriage of Imani Naomi Lenoa and Gyuu Nakamura their wealth was linked, which makes them one of, if not the wealthiest family in LMB. Goro is not the only grandchild in The Nakamura Family, but he is the wealthiest since he is Imani's only kid and eldest grandchild, making him the Heir to all the companies.

As for The Tanaka Family, they are also from old money, however, it's gang money. The Tanaka's are the wealthiest and most notorious family in the underground scene in LMB. 

They own most, if not all of the Brothels that run in the Red light Districts around Japan. The Tanaka family also owns multiple underground businesses and dip their hands in politics. The Tanaka Gang has 8,000 thousand members currently and 500 rookies in Training all over Japan. The Tanaka Syndicate's main headquarters however is Located in Tokyo, Japan. 

The Tanaka and Nakamura families are quite prominent. This will be covered more in the comic.

To put things into perspective, Goro owns Shoto, which makes him a property of The Nakamura's, which implies Shoto is automatically an asset to the Nakamura family, which protects him by association through Goro.

However, Goro does not even need the protection of his family name; he is quite well-known and has considerable authority on his own.

The contract between Shoto and Goro was not only a sexual one; it also included Shoto receiving protection from the Nakamura security resources through Goro.

Nevertheless, this does not imply that Shoto is completely safe from harm; he still remains a member of The Tanaka Family.

The Tanaka Family and Nakamura Family are both powerful families. 

I'm open to your comments -Kurutta.