The Japan international feels his game still has several gears to reach.
He told L'Equipe: "I have just reached a milestone by becoming one of the best players in La Liga. The next will be to try to become one of the best in the world. For that, as my coach (Imanol Alguacil) says, I have to overcome a statistical milestone. Last season I only scored seven goals. I'm still missing that little detail. When I get there, another door will open for me.
"I like to create things that others don't do. My thing is to face defenders one on one, put the ball between the lines, play forward... That's why I prefer to be in the centre of the field. I have always had a weakness for the number 10. I aspire to be a special footballer and for people to enjoy watching me."
Kubo added, "In the Japan team I have not evolved as I would have thought. I feel that the people and the staff do not have as much confidence in me as in Real Sociedad. In Japan they do not bet as much on me."