Getting involved in the corridors of power in the shogunate government, Mansai was cool in assessing the situation and warm in getting on with people, which was appreciated by his contemporaries as 'a loyal retainer of the whole country' ("Kanmon Nikki" (Diary of Imperial Prince Fushiminomiya Sadafusa) by Imperial Prince Fushiminomiya Sadafusa).
幕政の中枢にありながら情勢を冷静に判断し、人情に厚い満済の態度は、同時代人から「天下の義者」（伏見宮貞成親王『看聞日記』）と賞賛された。