Kimihiro Watanuki is cursed with the ability to see evil spirits known as Youkai. Due to this power, the Youkai are attracted to him like a magnet, and each time he is close to being devoured. One day, fate drew him to a strange store and there, he met Yuuko, who was dressed in a very exquisite fashion. As destiny would have it, Yuuko has the ability to save Kimihiro from seeing the Youkai, but for a price: Kimihiro must work for Yuuko by performing chores around the store and other odd tasks, until she deems fit. With his "friend" Doumeki, and his secret crush Himawari, they will discover that the world they live in is nowhere close to ordinary!
His name is Tortov Roddle, and he is a traveler from Tortalia. Along with his unusually large companion of a pig, the slender Tortov travels from place to place, always finding a new and beautiful adventure at his destination. From islands carried on the backs of frogs, to delightful cafes, to movie theaters and giant bears, there's a wonderful story to tell in the diary of Tortov Roddle.
Both anime share a similar mysterious and quietly fascinating atmosphere. They also both use similar musical scores, which wonderfully but subtly emphasize the spiritual mystery of each series. They are both episodic and each episode brings a new phenomenon for the viewer to get lost in. They are also both set in a fantasy world with magical and spiritual overtones, though in xxxHolic this world is juxtaposed with the standard school and town environment. What does notably distinguish them from each other is the humor of xxxHolic and the outrageous and raucous behavior of the protagonist Watanuki whose personality is the polar opposite of the reticent Tortov. Apart from the difference between the personalities of their respective protagonists, I think that someone who appreciated the elements I've mentioned in one of these anime would do well to watch the other.
Maebara Keiichi, an ordinary high-school boy, has transferred to a new school in Hinamizawa, a small rural village. At the outset everything seems peaceful and Keiichi becomes friends with a nice group of schoolgirls with whom he spends many idle summer afternoons. Suddenly violence encroaches upon the blissful peace of the village and Keiichi becomes entangled in an endless cycle of fear and death. The inconsistent, but inevitable horrors of Hinamizawa are told and retold becoming an endless and inescapable nightmare of insanity. Will it end even if the mystery of Hinamizawa is solved?
Nanami used to live in a ramshackle apartment with her father - a man who spent half his time gambling and the other half hiding from debt collectors - until one day the scoundrel ran away, leaving his daughter hungry and homeless. That is, until she meets a mysterious stranger in the park who deems her the new goddess of a local shrine! Unfortunately, Nanami’s new home is occupied by Tomoe, a fox familiar who objects to the presence of a mere mortal and immediately begins to bicker with the girl. If she can manage to form a contract with the troublesome man, he’ll be obligated to accept and help her perform her duties. But there’s a catch: Nanami has to kiss him first, and who’d want to lock lips with that awful guy?!
Shizuru and Mizuki are two quiet sisters who have a foot in the world of the supernatural. While Shizuru can see the spirits and monsters who haunt mankind, Mizuki can't help but become possessed by them. Together, the duo live with their grandparents and are taught about the spiritual world from their grandfather, a powerful exorcist. In the serene countryside, the girls will learn about the ghosts and goblins that co-exist in our world, while also learning about themselves and their abilities.
xxxHOLiC is more of a supernatural horror while Mokke is more of a supernatural fantasy, but they're still both episodic shows about supernatural creatures and phenomenons. They both have a tendancy to tell and show that dealing with these supernatural situations isn't all wonderful and happy, but that it can have serious and dangerous concequences.
In Norse mythology, the end of the world was foretold as the final war between the gods, and its name was Ragnarok. In a twist on the lore, the god Loki finds himself exiled to the world of humans. Mayura, a girl obsessed with mysteries, ends up entangled in Loki's struggle to return to the world of the gods without realizing it, and meanwhile, the gods divide into factions. Some are willing to help Loki find his way home, while others are after his life -- the end of the world, the final war: Ragnarok. And in the center of it all is Mayura...
In both series there is a person who is a very powerful and knowledgable mystic - Loki and Yuka. They take an ordinary person under their wing and help explain to them various aspects of the supernatural world. There is also an overarching mystery in both series.