Function LIKE with Japanese lang.

Hi, guys
I am trying to make select using LIKE function with Japanese language and it does not work sometimes.
I have phrase from several symbols with length 36 bytes (1 char 2 bytes), if I make a query with LIKE function it does not return me result if specify more than 3 characters in LIKE '%...%' clause.
It reurns me correct result if my field contains English & Japanese characters. In that case I can make a query using LIKE function based on more than 3 Japanese characters.

Any advices are very wellcome.

Oralce 8.1.6, Solaris