[TOMT] a favorite japanese series of me but I can’t remember

can you help me find this japanese series? its ancient time (although I’m not sure if it’s really an ancient time I remember they only use samurai at that time) , let’s put it in the main story or plot of the story, at the beginning the main character are poor or beggar and he goes into this restaurant and some rich or higher position are going touching his friend so he step in and made a line on the ground using his sword and says if you step in the line I’ll kill any of you and in the middle of the story he realize that he is one of the 8 or 7 prince and at the almost end of the story here’s a traitor among the organization and order one prince to kill the main character but he couldn’t kill his friend so he stab himself with a sword that has poison in it and died and the story goes on but I forget but at last moment where the prince died cause of the poison sword it’s almost at the end of the series.

please don’t ask me anymore question that’s all I remember and please help me find it I really want to watch it again because it is one of my favorite Japanese series when I’m still a child and I’m 16 now