Kami to Sengoku Seitokai

Katsuragi lost his parents in an accident and is now all alone. He missed the first months of school and now he arrives to be put through a lot of weird occurences. The school he is attending is said to be the center of the universe and he must fight to become the king. His opponent however was a crybaby he used to protect. Does he have what it takes to fight against his childhood friend, deal with girl problems and prove his nickname, the unsinkable?

'...if you actually decide to go for it... and do become president of the student council..'
'...i'll let you have your way with me'

'This school... is at the center of the entire universe'

'I belong to you... Musashi.'

Those were the words of Vice President of the Student Council, Kagura Mami that were said to Katsuragi Musashi on the first day they met.
What's the secret of that school? What's the mystery behind it all? And what's the past that haunts Kagura and Katsuragi?