Katsushika Hokusai was a Japanese artist, renowned during the Edo period for his paintings, prints, and woodblocks. As a child, he worked in a bookshop and later as an apprentice to a wood carver. He studied wood block printing from Katsukawa Shunshō and published his first prints in 1779.
Hokusai's work was greatly influenced by Chinese art of the time. He was famous for his block prints and his series One Hundred Views of Mount Fuji is generally considered a masterpiece. Hokusai had extensive influence in art, and even inspired European artists.
The Strong Oi Pouring Sake is a woodblock print depicting the legend of Oi. The theme is Oiko pouring sake to Fan Kuai, a legendary warrior general who lived between 241 to 203 BC during the Han dynasty. In the picture, Oi appears to be huge, especially in comparison to Fan Kuai, depicting the fact that Oi is indeed super-strong. Both are dressed in blue and red, showing their affinity as warriors. Fan Kuai appears to be relaxed and he is holding out his bowl while Oi pours the sake into it. To the top right is a caption explaining the theme of the picture.
The legend of Oiko is quite interesting in itself. She meets a man who is going to the capital and wants to become a sumo wrestler. He angers Oiko in a mistaken show of male machismo and gets defeated in a fight. The man comes to his senses and decides to stay with Oiko at her invitation. Oiko trains him and also prepares rice balls for him every day. The day he would be able to bite into them was the day he had excelled at his training. This man later becomes a famous sumo wrestler.
Another theme is that Oi is actually a representation of Hokusai's daughter, Sakae. The picture is a pun based on Sakae's name, which is similar to the alcohol drink. However, this theory is not confirmed by any primary sources.
The Japanese name of the picture is Combined pictures of the brave people from Japan and China, Ōiko and Fan Kuai, which really is a better description of the picture.