All rights belong to George RR martin. I am just writing this for fun.
The MC is first generation Japanese American.
He considers his reincarnation a new life. He will not cling on to modern sensibilities. He is ruthlessly pragmatic and kind of hedonistic. This is the super soldier serum from Marvel comics ultimate . So this captain America is roughly as strong as spider man so (10 ton range) . So quite Over powered for this setting but it will be balanced out by his utter lack of knowledge about the setting. The Serum also enhance the good and bad aspects of his personality so he will be an extreme character . The MC is quite ambitious and wrestling with good and bad parts of his own consciousness . There will be kind of Harem and smut But only one main love interest.