The line “waga shougai ni ippen no kui nashi!! / わが生涯に一片の悔いなし！！” (roughly “in all my life, not a single piece of regret!!”) is a line said by the character Raou from the manga Hokuto no Ken / Fist of the North Star while he does a specific pose.
Original
The standing pose is often used with various spellings of the line “waga shougai ni ippen no kui nashi!!” written on top of the image
Credit: 原作：武論尊、漫画：原 哲夫
Parodies:
It has been parodied in various anime
Bokutachi wa Benkyou ga Dekinai! / We Never Learn!: Bokuben
Sekijou Sawako: “waga jinsei ni kui nashi” (“in my life, no regrets”)
©筒井大志／集英社・ぼくたちは勉強ができない製作委員会
Dakara Boku wa, H ga Dekinai. / So, I Can’t Play H!
Kaga Ryousuke: “waga ero jinsei ni ippen no kui nashi” (“in my ero life, not a single piece of regret”)
(C) 橘ぱん・桂井よしあき/富士見書房 (C) 僕H製作委員会
Dumbbell Nan Kilo Moteru? / How Heavy Are the Dumbbells You Lift?
“waga sankaku kin ni ippen no yoryoku nashi” (“In my deltoids, not one piece of remaining strength”)
©2019 サンドロビッチ・ヤバ子，MAAM・小学館／シルバーマンジム
Kandagawa Jet Girls
Jennifer Peach: “Jennifer, waga jinsei ippen no kui nashi deesu” (“Jennifer, in my life, not a single piece of regret”)
©2019 KJG PARTNERS
MM!!
Himura Yukinojou: “waga jinsei ni ippen no kui ari” (“in my life, there was a single piece of regret”)
©松野秋鳴・メディアファクトリー／えむえむっ！製作委員会
Ore wo Suki nano wa Omae dake ka yo / Oresuki: Are You the Only One Who Loves Me?
Akino Sakura / Cosmos: “waga shougai ni ippen no kui nashi!!”
©2018 駱駝／KADOKAWA／「俺好き」製作委員会
Yahari Ore no Seishun Rabukome wa Machigatteiru. / My Youth Romantic Comedy Is Wrong, As I Expected / My Teen Romantic Comedy SNAFU
Zaimokuza Yoshiteru: “waga jinsei ni ippen no kui nashi” (“in my life, not a single piece of regret”)
©渡 航、小学館／やはりこの製作委員会はまちがっている。