Some TMNT stuff was always meant for grownups.
Mokoshan was a character that first appeared in Teenage Mutant Ninja Turtles Adventures issue #67: Of Wolves and Men. He is a wolf-man that would encounter the turtles, Ninjara, and April O'Neil. He was the mate of Nei'Sha, which he lost at the hands of a hunter. He would eventually meet Ninjara who became very attracted to him. After separating from the turtles, he and Ninjara would eventually become mates. He was the father of Moka.
Teenage Mutant Ninja Turtles Adventures
Mokoshan first appeared in issue #67. He's shown in the beginning out in the Alaskan wilderness, enjoying the first snow of winter with his beloved mate Nei'Sha. As she was cried out a song to him, she's suddenly shot by human hunters before his eyes. Stricken with grief, Mokoshan cries a howl of grief as he held her in his arms. His howl was carried over the wilderness by packs of wolves. Ninjara heard the cries and found them similar to her fox people.
In issue #68: The Howling of Distant Tomorrows, Mokoshan is very hostile to the group and continues to make threats. But he his threats decease when he sees Ninjara and becomes smitten by her appearance. He quickly dubs her "Moon-Eyes", complimenting her on her beauty. Naturally, Ninjara's boyfriend Raphael is uncomfortable and tries intervene. Mokoshan quickly vanishes but not before promising to see her again. Leaving Ninjara, equally smitten by his actions. Later through the camping trip, Ninjara admits she's intrigued by the him.
He would appear again after Ninjara is critically injured by a hunter, who shot her by accident. He comes to her aid, promising that his peoples' medicine could save her and quickly disappears with her. Though Raph tries to intervene, the blizzard's harshness prevents him from going after her.
Later on in issue #69: Twilight, Ninjara would awaken among Mokoshan's cave dwelling home. With a wolf-woman Revyen who was hinted to be very jealous of her, most likely hinting she wanted Mokoshan's attentions with his co-leader gone. When she painfully checks Ninjara's bandages and causes her to fall out and cry, Mokoshan quickly comes to her aid and kicks Revyen out. During the night, Mokoshan and his people performed a service for his deceased mate and set body ablaze in a funeral pyre. Ninjara awoke to them howling Nei'Sha a farewell. When he explains whom the funeral was for, he later helps Ninjara back to her room as she was still groggy from her injuries.
In issue #70: A Dusk, a Dawn, Mokoshan shows her around his village. He explains to her that only the Native Americans know of his tribe's existence because modern people wouldn't understand them, and that his people and the Indians came to Alaska over an ice bridge many centuries ago. Ninjara realizes that her fox people and his share a common ancestry. As the day changes two begin to bond even closer. Unknown to her the turtles are still looking for her and that Raph had finally reached the village. But he had been found by a very jealous Revyen, who was set to start trouble for Ninjara (or perhaps break her bond with Mokoshan). When he instantly asks Ninjara's whereabouts, Revyen is quick to show him where she is, with Mokoshan.
Infuriated, Raph smashes through the window and starts a fight with Mokoshan, though he has no interest to fight. Unknown to them, Revyen is sinisterly watching them fight. Before a victor can be determined, though, April and the Turtles come barreling through the briar patch with the polar bears hot behind them. Donatello asks Mokoshan to create a diversion and the wolf-man sets the caribou free from their pen. As the caribou race off over the hills, the bears chase after them and abandon the village. Still weak, and made even weaker by all the action, Ninjara faints and Mokoshan quickly comes to her aid, taking her back to her room.
Raph sees he's lost the battle for good. Later Ninjara and April have a chat sitting on a cliff-side. She admits she's attracted to Mokoshan's charm and good looks, mostly his peaceful and positive disposition compared to Raph's bad attitude. Raph eventually approaches the two and talks with Ninjara alone. The two tearfully agree it was best to break up and kiss each other goodbye.
When the others leave, Ninjara stays behind in Mokoshan's village to be with him.
After TMNT Adventures
Since Ninjara was created by Stephen Murphy and Chris Allan rather than Kevin Eastman or Peter Laird, after the Archie series ended they were allowed to continue using both her and Mokoshan. He is referenced, but does not appear personally, in Ninjara: Seed of Destruction, a story arc published in Furrlough, a furry fandom stories magazine from Radio Comix. Ninjara and Mokoshan had become mates and had a child named Moka, but Mokoshan had later been killed but the same human sniper who killed Mokoshan's previous mate Nei'Sha. After Mokoshan's death, Ninjara left the tribe, taking Moka with her to Japan.