This game could appeal to a wider audience but it is not marketed well to them.

It relies only on two groups of gamers: hardcore SEGA fans who love this franchise by default & MALE gamers who happen to like brawlers

That’s simply not true, there are tons of gamers who are in to this from the cultural aspect. Exploring the city streets of Kamurocho and in the more recent games the other parts of Japan. Playing the game on Easy Mode to just enjoy the story unfolding and escaping to Tokyo.

The brawling is fun but if what you were saying is true the demos for Yakuza 3 and 4 on PSN would have brought in a lot more players instead of being passed off by many as a low budget brawler. A series that has more heart put in to it than almost any franchise that is around today is being passed off as “just a brawler” by the mainstream audience.

The series has an image problem in the west, I can agree with that. But it is not the fault of the game. It is the fault of the marketing. Instead of targeting the hardcore Call of Duty audience with big budget adverts or even the trailers for Dead Souls that did not appeal to ANYONE. They fail to capture what is best about the game as an experience. 

I point to Persona series and Atlus as publishers that know how to market an EXTREMELY niche hardcore Japanese franchise. They manage to make it profitable (even on the Vita!). They know how to reach their audience, create trailers and demos that appeal and explain what the game is about better than any other import publisher.

Sega needs to tap in to that market. Don’t waste advertising dollars on sites like IGN or Gamespot. Put that money towards smaller communities, specifically RPG players and anime watchers. Japanator, anime services like Crunchyroll or Magazines like Shonen Jump would reach the EXACT type of person who would be interested in this series. Male or female they are predisposed to that kind of culture. They are hungry to experience more. It doesn’t matter that they don’t review well in the west because most niche Japanese games don’t. You’re trying to bring in a mass market appeal where none exists. This is a niche game for a niche audience. If they are worried about production costs have a smaller product run. Plan for only a small amount of players to pick up the title and if it does well, do a second print. Maximize profits.

The only part I can agree with you on is how unfortunate it is that Sega may see this series as unmarketable outside of Japan. When the reality is they are just targeting the wrong audience.