At the end of Gaiden vol 2 we see Goujun being ahh escorted away by Tenpou, to save new comers from spoilers. The start of the next ep has Goujun sitting at his desk among the cherry blossoms, writing 'I am the only one who can relate what happened next'- after they went to Tenpou's- because Goujun was the only person with the four in the upper rooms. Goujun also has a scar across one eye. Meaning: time has passed, the Konzen-tachi are gone/ dead, and Goujun didn't die with them because he's still in Heaven writing either a report or his memoirs.
So if he *didn't* die but he *is* Jiip how did it happen? When in doubt, follow the original source, say I.
Thanks are obviously due to mauvecloud for poking the plot bunny into existence, and to the long-ago poster either here or at Kagenami's who suggested that Litouten might well have done the eye for an eye routine with Goujun.