A-Ranku Pâtî wo Ridatsu Shita Ore wa, Moto Oshiego-tachi to Meikyû Shinbu wo Mezasu.

The original story is quite good for yet another "leaving my party" story that is quite the trope nowadays. Here, an amazing "Red Mage" makes a Harem of talented adventurers (that, obviously, all fall in love with him), and together they climb the Ranks until involved in a world-saving scenario. Dungeon diving, rivals, black magic and more.

As an adaptation, it is somewhat disappointing in the visual department. The animation itself is okay.. but then you see still images from the actual episodes themselves being used in the Opening! So, you start wondering about the budget.. And while the style of this anime is good, it doesn't capture the gorgeous look of the source material (specially with the female leads). But it flows well and the (JP) voice casting is good.

EDIT: Sadly, as more episodes release, it is quite evident that a LOT of plot points were skipped and some gore-y and "inappropriate" elements completely removed (understandably)! Ones that gave this series a darker tone, but a distinctive personality. I'm not sure how I would feel as the creator, but it even rewrites some of the developments.. This isn't a proper adaptation, but a summary in parts, and takes the liberties to rewrite others.

Personally, I would recommend the Manga instead (if you prefer a more detailed and adult story). But Anime is always a much more digestible medium, and does away with what some would consider unnecessary.