Even if only his belly button was black, even if there was just a tiny bit of obsession, it could represent his identity as an "evil corpse" and wouldn't disgrace the evil corpses.
After examining his belly button, the evil corpse in white, Shuhang, let his shirt fall back down and elegantly tidied his clothes.
With his white-robed scholar attire, his "gentle and warm" appearance, and his elegant and unrestrained movements, he looked exactly like a scholar and gentleman who had stepped out of an ancient painting.
Perhaps his appearance was the only aspect of Song Shuhang that hadn't been absorbed by Song Youyou.
After straightening himself up, the evil corpse in white, Shuhang, bowed to Song Shuhang and said indifferently, "This poor monk is Ba Er. Greetings, Senior."
As the first corpse of the three corpses, he was formed from Song Shuhang's "malicious obsession," the Godly Overlord Pillar, and the inner demon carrier.