Bone Flesh Unity Gu

One is green and one is red. They are tied together like two jade bracelets and quietly let out warm luster as they hover. ^{ch. 226} They are green as grass and red as blood, tied together so they cannot be separated. ^{ch. 229}

The Bai Gu mountain hall holds unfinished materials and a scroll: refinement needs two blood-related Gu Masters, and Gray Bone Scholar dies before finishing the experiment himself. Fang Yuan and Bai Ning Bing run the forge steps there. At the final flesh step Fang Yuan throws in the Bai clan twins Bai Sheng and Bai Hua first; the twins burn to death, and the fire turns scarlet but fails to reach reddish-purple, so that step fails. Fang Yuan and Bai Ning Bing then cut their own flesh into the fire. When Bai Ning Bing’s flesh lands, the fire turns reddish-purple; they pour primeval essence together, and a linked green-and-red jade bracelet pair forms. Fang Yuan alone takes the pair and instantly refines it into his aperture before they flee. ^{ch. 226} The bracelet pair still sits in Fang Yuan’s aperture. ^{ch. 229}

Bai Ning Bing refines the red half after Fang Yuan removes his imprint and cooperates. When she finishes, the bracelets dissipate and become circular marks on the wrists (green on Fang Yuan’s left, red on Bai Ning Bing’s right), leaving a sense of linked flesh and blood between them. ^{ch. 230}

It converts another Gu Master’s primeval essence into the receiver’s own aura during transfer, so the essence can be used to wash and refine the aperture without the usual mixed-aura problem of ordinary imparting. ^{ch. 226} The Gu is a series, not a single fixed worm. Quality depends on how deep the relation is between the refiners, from low to high: fratricidal, friendly relation, indissoluble relation, familial relation, and blood kin relation. Conversion efficiency rises with that quality: fratricidal keeps one-fifth of a ten-percent transfer, friendly two-fifth, indissoluble three-fifth, familial four-fifth, and blood kin the full amount. ^{ch. 230}

Fang Yuan and Bai Ning Bing hold the mid-quality indissoluble relation form, a rank three Gu. That mid quality is the middle result of mixing the twins’ deep blood-kin relation with Fang Yuan and Bai Ning Bing’s fratricidal-level relation, after Fang Yuan tampers with the recipe at the last step. ^{ch. 230} With it, Bai Ning Bing’s snow silver essence can drive Fang Yuan’s early breakthroughs far faster than liquor-worm methods alone, including help when breaking a large realm. ^{ch. 230 ch. 231}

After both refine the pair, they cultivate by pressing palms and moving essence through the marks. ^{ch. 230} One night of that method raises Fang Yuan from rank one upper stage to rank one peak stage. He values the Gu above Blood Skull Gu and Heavenly Essence Treasure Lotus in that stretch, below only Spring Autumn Cicada. ^{ch. 231}

When both finish refining, the linked jade bracelets dissipate and become circular marks on the wrists, green on Fang Yuan’s left and red on Bai Ning Bing’s right. ^{ch. 230} In Shang clan city the Gu sits as a bracelet tattoo on his arm. ^{ch. 273}

On the caravan road they sit with Bai Ning Bing’s palms on Fang Yuan’s back. Ten percent of her snow silver essence flows out; Bone Flesh Unity Gu shines green and red and converts it so six percent enters Fang Yuan’s aperture. ^{ch. 245} In Shang clan city the same method breaks him from rank two peak stage into rank three initial stage in about six hours, while the Gu sits as a bracelet tattoo on his arm outside the aperture Gu list. ^{ch. 273}

When Bai Ning Bing reaches rank four and Fang Yuan is still rank three peak stage, he judges that once their cultivation matches, Bone Flesh Unity Gu will help him much less, which is why he pushes for a rank four nine eyes liquor worm. ^{ch. 326} Bai Ning Bing’s rank four light gold essence through the Gu is still decisive when he breaks into rank four: after his own snow silver essence empties at the border, her waterfall of light gold essence finishes the aperture-wall collapse. He credits Bone Flesh Unity Gu, Bai Ning Bing, and Shang clan city’s environment for that two-to-three-year climb. ^{ch. 331}

Fang Yuan still treats the rank three Gu as valuable because many Gu Masters can use it even at that rank, and groups it with Self-reliance Gu as a worm that need not match the owner’s rank to stay useful. ^{ch. 345} After he reaches rank four initial stage and the poison vow is gone, he tells himself he already has no need for Bone Flesh Unity Gu and delays saving Bai Ning Bing so he can cultivate past her. ^{ch. 355} Later at San Cha mountain the transfer runs the other way: with nine eyes liquor worm purifying his bright gold essence into essence gold, he pours that essence into Bai Ning Bing’s rank four initial stage aperture through the Gu and helps nourish her walls. ^{ch. 365}

When he cannot use several worms in Northern Plains, he leaves Bone Flesh Unity Gu in Hu Immortal blessed land with Blood Skull Gu, yin-yang rotation Gu, and other Gu that are not useful at that moment. ^{ch. 504} Rank three Bone Flesh Unity Gu still sits among what remains in Hu Immortal blessed land, not as something he and Bai Ning Bing still hold together in his aperture. ^{ch. 581} No cited later chapter describes the pair’s fate after that inventory line.