This is both a manga and an anime, but the anime adaptation is very faithful.
So there's this super-grouchy teenager, Ichigo Kurosaki, who has bright orange hair and can see ghosts. Like many anime characters, his hair color is natural despite the fact that he's Japanese, and it has caused him great angst and teasing. It probably doesn't help that his first name is a homonym for "strawberry," though it actually means something like "protect one thing." He has two little sisters and a crazy doctor father.
One day this great big hideous demon attacks his house, and a tiny but very determined woman in cool black robes and a sword shows up to destroy it. But things go wrong, and the woman, Rukia, has to transfer her shinigami (Soul Reaper) powers to Ichigo so he can kill it and protect his family. Next thing Ichigo knows, he has cool black robes of his own (which suit him much better than the hideous pimp jacket he wears in the opening credits), an ENORMOUS sword, and a mission: to send the demons, which are called Hollows and are corrupted souls that devour humans and normal ghosts, to their final rest.
He also has Rukia living in his closet. Because she lost her powers, she has to pretend to be a schoolgirl while she coaches him. In the anime, she normally speaks in gruff, extremely macho terms, but when she's in her schoolgirl persona, she puts on his horrifying, super-feminine voice that is the funniest thing ever. Also, since she came from the Soul Society (spirit world) things like juice boxes are quite new to her. She has a magic cellphone and takes no guff from anyone.
In a lot of ways this is a typical shounen series, with lots of fighting against increasingly powerful foes, with corresponding increases in the heroes' power levels, and much repeating of that shounen motto, "I will become stronger!" But it's an excellent example of one. The characters are really likable and quirky-- I adore Ichigo, Rukia, and the entire pre-Soul Society supporting cast-- the dialogue and situations are often very funny and sometimes poignant, and the mangaka has a wonderfully insane way with chapter titles, like "Quincy Archer hates you," "DER FREISCHÜTZ King," or "Second Contact (it was beyond the scope of our understanding)."
The poems at the start of each volume are sometimes quite lovely. I think my favorite, which sums up what I love about shounen, is, "Without my sword, how can I protect you? With my sword, how can I embrace you?"
In the manga, the episode about Ichigo's mother is more poignant, less sappy, and more surprising; also, Orihime is more interesting and quirky in the manga. And any annoying characters, like Ichigo's lunatic father, are bound to be less irritating in print, where they're silent. Orihime's enormous breasts are also less distracting when they don't move.
The anime, though it doesn't have the world's greatest production values and loses some detail and subtlety, has the huge advantage of Rukia's brilliant voice actress. I also enjoy seeing Ichigo's bright hair in color. Also, some of the humor was way more effective for me in motion than on the page. Rukia vs. the evil juice box, the insane parakeet episode
, and the living teddy bear were all much funnier in the anime. In fact, I would recommend this series just for the parakeet of DOOOOOOOM.
The series eventually takes a plot turn that I have problems with, but it's still quite addictive.