If you mean abnormal sister love or sister complex it would be シスコン /shi su kon/.
シスターへの愛 /shi su taa e no ai/ would be your phrase translated into Japanese. Since they have two different words [Imouto : younger sister / Ane/Nee-san : elder sister] for elder and younger sisters I wasn't sure which you meant.
The sentence 'I love my sister' would be 姉が大好きです (ane ga daisuki desu) in Japanese when talking about one's older sister. To say 'I love my sister' when referring to a younger sister, you would say 妹が大好きです (imouto ga daisuki desu).
You may say 'imouto.'
zan zumi
aisuru or aishtte iru is love in Japanese for people daisuki is love for things
To say "i love you" in japanese: ai shi teru Ah-shee-tare- oo
Ai
aishitteiru
since when does Jacob speak Japanese?
Sukidayo ^^^ that means i like you. Love is pronounced as Ahh-E Say ahh and say "E" like the letter.
You could say "kimiga hoshiindesu" which means "i want you (in a sexual way.)" Hope that helps :)
"neko no onesan" which basically means "cat's big sister"
The term 'little sister' could be translated as 'imouto', to say 'my little sister' you could say 'watashi no imouto'. But remember, if you are going to refer to someone else's little sister, you must say 'imouto-san', 'san' being the honorific, which are a key element of the Japanese language and etiquette.