Lit. Heart
Shin is the first aspect of Shin Gi Tai.
It is the most important part. Tai and Gi are the basics, you cannot Win without them, but they are a matter of basic Keiko, they are of utmost importance to the beginner.
Shin means being strong of Heart. It means possessing Indomitable Courage. Shin means being a Hero.
What makes a real Warrior is Shin.
Shin is the Heart of a Warrior.
Having Shin means having an iron Heart so that you are a real Warrior. You never budge. Never hesitate. You are always ready to Prove Yourself.
Only by forging the Shin can you rise to the top, defeat any Aite.
Through focusing on Shin no Fear will stop you because you are the embodiment of Courage.
It is Shin that allows you to Fight with full Power. If you have honed your Shin in the fire of your Will, you will exert maximum Power, being Indomitable Fierce.
On the 2nd day of Kyuushuubasho 2006 Aminishiki fought and lost convincingly, without generating any forceful resistance. Yet this was the same Aminishiki who beat Yokodzuna Asashouryuu on day of . It was because the intensity that Aminishiki was able to generate for his victorious Shoubu with Asashouryuu allowed him to put all his might into the Shoubu. But he was not able to maintain the intensity in every Shoubu. Asashouryuu on the other hand is exemplary in Fighting with Superior Intensity in most Shoubu. He fought Futen'ou on the same 2nd day of Kyuushuubasho 2006. After the Tachiai Futen'ou got Hidarizashi and pushed Asashouryuu forcefully to the Tawara, almost Winning right there. However Asashouryuu refused to give up in a losing position and with great determination resisted, pushed Futen'ou back and won. This is what Shin is.
It is Believing that you are Superior and acting accordingly with that belief. Never giving up, realizing that it is expected of you that you Win and that you cannot allow yourself to be Weak and Lose. This is what Sumou is about.
It is the Heart of a Yokodzuna. My Shishou, Naruto Oyakata once told me this sentence in exactly these words.