In Street Fighter 6, Gouki aka Akuma, performs his iconic finishing move, the Shungokusatsu (瞬獄殺, "instant hell slaying", or alternatively, "imprisoning death flash"), whilst reciting the following poem:
一瞬千撃 抜山蓋世 鬼哭啾啾 故豪鬼成
Isshun sengeki, batsuzangaisei, kikokushuushuu, yue (ni) Gouki (ni) naru
On a surface level, a literal translation of this would be: "A thousand strikes in one instant. Piercing mountains and covering worlds. Oni's restlessly wail and whimper, therefore, I become the mighty oni."
But there more to this, two of the lines are idioms (抜山蓋世 鬼哭啾啾), whose figurative meanings renders the poem translation as:
"A thousand strikes in an instant. Having herculean strength, the spine-chilling wailing of restless ghosts, for this reason, I am become the mighty oni"
You can take it both ways, but the very last line is written in the format of Classical Chinese poetry:
故豪鬼成
Yue (ni) Gouki (ni) naru
"Therefore I become the mighty oni"
"Mighty oni" itself being a literal translation of his own name Gouki.
These lines are in turn a reference to a moment in Masahiko Nakahira's Street Fighter Zero manga series.
The move itself takes usually, in the games, the form of Gouki floating towards the enemy, grabbing them and in a flash they lay defeated at his feet, and he displays the kanji for "heaven"(天) on his back.
UPDATE:
This has also been covered quite thoroughly on Eventhubs, though there are a few errors such as translating Gouki's name as "proud demon" rather than "mighty oni".