Black Dragon in Chinese / Japanese...

玄龍 is a sophisticated or scholarly way to say “Black Dragon.”

玄龍 is the title you'd expect in ancient Chinese literature.

The first character means black or mysterious.

The second character means dragon.

This black dragon represents a king dwelling in the depths of the mystic waters.

墨龍 is a cool way to say “Black Dragon.”

墨龍 is literally “Ink Dragon.” The ink part is black Chinese ink, the deepest, darkest ink available for thousands of years.

黒龍 is a generic title for “Black Dragon.”

The first character is black color.
The second means dragon.

Sometimes written as 黑龍 (just a minor variation in the first character).

This is the Japanese martial arts title Black Dragon Ninjitsu or Black Dragon Ninjutsu in Kanji.

黑龍之家 was added by special request of a customer. This phase is natural in Chinese, but it is not a common or ancient title.

The first character is black.
The second is dragon.
The third is a possessive modifier (like making “dragon” into “dragon's”).
The fourth character means home (but in some context can mean “family” - however, here it would generally be understood as “home”).