Konoha's Top Miner Is Reborn as the Sea Folk's Savior

Infinite Tsukuyomi Version:

Uchiha Obito is reborn as the proprietor of the merfolk... and the fish princess's battle partner. His rivals include, but aren't limited to: Kisame, chief of the shark clan; Deidara, prince of the starfish clan; Hidan, a leech spirit; and Kakuzu, the dragon-turtle financial officer. He also sees a red hermit crab and a blue sea butterfly darting and playing in a giant orange anemone. Most importantly, the green tea seahorse monster who can bear the burden of pregnancy for the merfolk is actually his charming ancestor... Who could have imagined the Akatsuki would reunite under the sea like this?

He thought nothing could be more bizarre, until he met the white merfolk kept by his sister-obsessed wife's eldest sister, the God of War. His old friend had become a mermaid, was too helpless to care for himself, and was so stupid he was growing a cactus at the bottom of the sea. A little turtle carried the cactus to the surface to sunbathe. But in the eternal Rinnegan forged by divine power, what Obito saw was a pair of Konoha's youthful jumpsuit-wearing master and student. Obito figured he must be under the Infinite Tsukuyomi. This was too damn ridiculous. To wake up as soon as possible, he was forced to establish the Uchiha Aquaculture Research Institute and manage his wife's little wives... One day, he awoke from the nightmare and returned to the shinobi world. Determined to build up good karma and avoid repeating the same mistakes, he decided to establish the Akatsuki and save his wife and the world!

Limited Tsukuyomi Version:

Uchiha Obito died and was finally about to go to the Pure Land with Rin, just as he'd always wanted.

He opened his eyes to find himself on the seafloor, surrounded by coral and a group of pretty fish-tailed things pointing at him.

He'd become a salted fish who couldn't swim, and a low-ranking male concubine even the servants dared to kick around.

So what if people bullied him? He already thought he deserved to die.

This was probably retribution for all the bad things he'd done.

Obito lay flat, quite literally.

Until one night, the Sea Lord, suffering the backlash of a charm technique, pinned him down and engaged in dual cultivation with him all night. Then Obito finally understood Uchiha Madara and his former self from the bottom of his heart.

Let this world be destroyed already.

And then the world really was destroyed.

Back in the shinobi world once more, he was just about to set out to carry out the "Eye of the Moon Plan 2.0" when he stepped on a blood-soaked woman with a beautiful fish tail. When she pinned him down and engaged in dual cultivation with him again, he felt nothing.

Much later, the woman came to her senses and rubbed her temples. "Who are you?"

Obito stared expressionlessly at the sky.

This fucked-up world should hurry up and explode.

In short, in this life, Uchiha Obito becomes a true savior.

A pure fetish project. Major OOC warning.

The heroine isn't a good person. Both leads are idealists, wandering alone through a dark world due to one twist of fate after another.

Theme: Rebirth is a kind of love for you.