The Japanese youngster reflected on his time at Mallorca positively, even if things didn't go as planned for the team.
"The club have made me grow as a player and as a person," he said of Mallorca to France Football.
"I leave great friends with whom I have shared great and bad moments.
"I will always remember the treatment from the people of the island.
"It has been an unforgettable season."
Kubo spoke about his playing style as well as the attitude he seeks to impose while on the field.
"I like to receive the ball between the lines and face [opponents] one-on-one, to be decisive," he said.
"I like to dribble, this is what I have learned playing football.
"I have many years ahead and a lot of room for progress. When I was little I played a lot of football, from 08:00 in the morning until dark. I never got tired. It was my life, my passion.
"I just wanted to improve. On the field I am never shy. If you are, you won't grow. On the field, it's your game that speaks."