Just watched episodes 12 and 13 of season 3. I'm speechless.
The story went places I couldn't even imagine. An alternate reality playing out like that was heart-wrenching. A cascade of worsening events, down to the darkest pits of what a human can go through. I've never witnessed a story like this.
The diary comes from an older Rudy who spent his last years building time magic to warn himself. It starts with Roxy. On Hitogami's advice he opens the basement, a rat carrying petrification disease gets out, and Roxy dies of it. Sylphy gets pulled into Ariel's rebellion. It fails and she's captured and executed.
The point where it broke me: Rudy seeing Sylphy attacked by the crowds. After that he completely lost his humanness. It had a Star Wars Emperor feeling. He killed the first person, then incarcerated like 20 people and torched the whole kingdom in revenge for Sylphy. Out of character, but it made sense for where he was.
Then him becoming like his dad, an alcoholic drowning his sorrows. A man losing himself. A man giving up on himself. It took a lot for him to change. He found other ways to channel his energy, which led to Zanoba creating a copy of Sylphy as an android or mechanoid or something. Rudy destroyed it again. Then he lost even more people. Eris comes back to save him. He pushes her away. Later she dies protecting him.
It aired today on Wife Appreciation Day. Don't know if that was planned. Crazy coincidence, him losing his harem today.
It's not perfect. It has its ups and downs. But it's such a potent story. Not boilerplate, not cookie cutter. Very original in how it tells one of the many isekai. Best isekai there has ever been. I can't think of anything that comes even close.