DB Chapter 413
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
"Gohan's Pain" (苦しむ孫悟飯, Kurushimu Son Gohan; Literally meaning "Son Gohan in Agony") is chapter 413 of the Dragon Ball manga.
Gohan screams, "FATHERRRRRRRRRR!!!!!", and pounds the ground. The others say nothing, and just look down (except Vegeta). The announcer wonders what happened and why Cell is gone. Kuririn walks over to Gohan and pats him on the back, saying he and Goku have ended it now. "It's my fault... I could've killed him back then, like my father said... I got carried away..." Kuririn says the Earth is still safe at least, and helps Gohan to stand up again. Kuririn picks up No. 18, who's still unconscious, and tells Gohan that Goku looked pleased when he died, since he was happy about Gohan's growth. In the other world, Goku apologizes to Bubbles and Kaiō, as the three of them all now have halos. They're all flying along next to Snake Road. Kaiō is pissed that Goku used him, the greatest in the universe, just to save one little planet. Goku says he's apologized, and that was the only thing he could think of at the time.
Goku says Cell's soul isn't here though, and wonders if he didn't go straight to Hell. Kaiō thinks about it, and then freaks out. He says everyone who dies has to go to Enma so he can say where their soul will go; meaning Cell must still be alive! Back on Earth, Vegeta asks Kuririn what he's doing with that artificial human, kill it. But Kuririn says he doesn't think she's that bad. Then, suddenly, something appears behind them all, like an explosion. They all recognize that ki, and out of the smoke, a blast comes through that suddenly shoots Trunks through the chest. As the smoke clears we see Cell's hand, and he asks who he hit, Trunks? The smoke has now entirely cleared enough that Cell is completely visible, and he has crackly lightning surrounding him, meaning now he's transformed just like Gohan. Everyone is shocked.
"Within my head is a small mass. That's what makes up my nucleus. As long as that mass isn't destroyed, my body can still regenerate. I was fortunate that when I blew myself up, my nucleus wasn't damaged. Frankly, I didn't think I could regenerate. I was lucky. It made me even happier that even without No. 18, my body regenerated to my perfect form. But not just my perfect form. I had greatly powered up just like Son Gohan. Perhaps it was my Saiyan cells that greatly raised my power from being saved at the brink of life and death. Additionally, I was able to study Son Goku's Shunkan-Idō. Or rather, I was able to perfect it and come back here. While Son Goku meant to defeat me, he just gave me many presents." The others are speechless, while Vegeta is pissed about Trunks. Gohan is silent, and gets serious again.