First off, this manga anthology may as well be called Fate/Grand Spoilers. The entirety of the second arc of Fate/Grand Order, the Lostbelts, is spoiled, so take that a firm and early warning that this best read after you have already read the entirety of Part 2, all the way to the end of Natlan. If you are willing to accept that, I absolutely recommend this, as these side stories enrich the narrative of the Lostbelts by providing scenes that give a glimpse at everything that was not displayed in the game. The art is all right, nothing particularly amazing. The main draw is always thecharacters and the side stories that did not fit into the Lostbelt. Some are incredibly touching, others fill in or expand on missing details that were not shown in the game. Since this is an anthology, it loosely follows the overarching order of the Lostbelts, and as the title lets you know, the key figures are the figures who fit into the Lostbelt arc, be they Crypter, Lostbelt King, or Other. Flashbacks to the past, concurrent views to the present, thoughts of the future, each vignette is made poignant by knowing who the characters are and what happened to them in their story, which makes it a tug on the heartstring. The stronger you bonded with certain characters during their Lostbelts, the better the reader experience from reading this anthology, which ultimately means this is for the fans. And what a wonderful present it is for the fans!

It's my personal opinion that the British Lostbelt had some of the best stories, but no matter which Lostbelt was your favorite, the anthology delivered. Strongly recommend to all fans of Fate/Grand Order, especially those who have completed the second part. Alternatively, read chapter by chapter, in alignment with your progress through the story. Totally worth it!