Depends what kind of Sibling Love you mean, but here's what comes to mind....
Cardcaptor Sakura, (This sort of qualifies, as Tomoyo is Sakura's Cousin, plus one other character, that is only revealed as such in Series 2)
Candy Boy, (weird Title, but a imaginative series that's well animated)
Chibi Vampire, (Anju Maaka would do anything to protect Karin, There's a Manga & co-current Novel Series too ; )
.Hack//Legend of the Twilight, (sort of)
King of Thorn, (Anime Film, quite dark but as good an example as any, although the Manga is more detailed)
Vampire Knight, (in many sense's of the word, can't say more or I'd give away what happens, & that would spoil the suspense ; )
Sakura Tsuushin, (aka "Sakura Diaries", the two main characters are Cousin's also, but this series is for 16+)
Other Series that qualify (Available as Manga only, as they are yet to be made into Anime Series, all the Anime above have their own Manga series)
A Wish of my Sister, (i know this only by reputation, & apparently it's a rather strong one, not for younger readers that's for sure)
Suzunari!, (two volume series, this is both Kawaii, & very funny ; )
Pretty Face, (a six Volume series, that covers multiple genres very well, & is outright hilarious)
|