Characters stomping Sephiroth on his back, from left to right, starting with the top row:
Row 1: Kazuya Mishima (Tekken), Jin Kazama (Tekken), Akira Yuki (Virtua Fighter).
Row 2: Ryo Sakazaki (The King of Fighters), Yuko (Valis), Wynn (Mystery of Atlantis).
It's time to give Sephiroth a humiliation conga he will never forget as punishment for all his villainy, just like how Gary Oak was given a humiliation conga for bullying Ash Ketchum, and justice will be delivered my way.
If there is anything Sephiroth will regret, it would be running afoul of the Mishima Clan and the curse they have been synonymous with throughout the history of the Tekken franchise. Sephiroth will be as good as dead just like Kazuya's father Heihachi Mishima because while Kazuya perished at the hands of Heihachi before, G Corporation resurrected Kazuya, and he came back stronger than before. This proved crucial in Kazuya's final showdown with Heihachi in Tekken 7, where Kazuya finally defeated (and killed) Heihachi.
If there is anybody who will get Kazuya dead and ultimately end the curse of the Mishima Clan, it will be Kazuya's son Jin Kazama. This hero is determined to eliminate the biggest, baddest villains, even if it means starting a global war. Therefore, no villain, not even a serial killer like Sephiroth, is safe from Jin Kazama and his Iron Fist of Justice.
If there is any reason for Sega to be angry with Square Enix, it's because Square Enix's allegiance to Sony contributed to Sega's exit from hardware production. For all we know, Jenova could have been colluding with a malevolent purple polygonal head who seeks to destroy the entire PlayStation All-Stars Battle Royale roster and become the sole mascot of PlayStation as payback for being rejected by Ken Kutaragi. That's why Virtua Fighter's Akira Yuki is stomping Sephiroth. Talk about payback for Sega being kicked out of hardware production by Sony, and Square Enix was largely to blame for Sega's exit.
Remember when SNK and Square Enix had a copyright dispute? Well, SNK can vent their anger on Square Enix by having Ryo Sakazaki, the leader of the Art of Fighting Team from The King of Fighters series, stomp on Sephiroth.
As for Yuko and Wynn, these two obscure characters get to vent their anger on Sephiroth, just like how they vented their anger on Gary Oak in the previous stomping comic, and all in the name of justice.
If you want to know why the shirtless Sephiroth is being stomped in this comic is because this is a reference to Sephiroth being in that alternate costume when he got slashed to death by Cloud's Omnislash at the end of Final Fantasy VII.