It was libpredict.so that is required to convert Romaji to Hiragana which I least suspected... I changed one of the letters in Korean keymap to 'a' and when I typed it converted into Hiragana although device had soft reset soon after. I assume it's a soft reset because SSH connection was not disconnected during 'the boy under the tree' screen with a progress bar.
[root@kindle ja.ko]# ldd libpredictor.so
/usr/lib/libenvload.so (0x40138000)
libwlf.so => /usr/lib/libwlf.so (0x40056000)
libicuuc.so.50 => /usr/lib/libicuuc.so.50 (0x401d3000)
libglib-2.0.so.0 => /usr/lib/libglib-2.0.so.0 (0x402fc000)
libc.so.6 => /lib/libc.so.6 (0x403f4000)
libiwnn.so => /usr/lib/libiwnn.so (0x400d1000)
libicudata.so.50 => /usr/lib/libicudata.so.50 (0x40522000)
libpthread.so.0 => /lib/libpthread.so.0 (0x40141000)
libdl.so.2 => /lib/libdl.so.2 (0x40161000)
libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x4123b000)
libm.so.6 => /lib/libm.so.6 (0x41306000)
libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x40077000)
/lib/ld-linux.so.3 (0x400a9000)
libicudata.so is presumed to be the one I'm looking for. I'm going to find some patterns of unicode of Japanese characters inside that library. International Components for Unicode(ICU) project is an open source project. (
http://site.icu-project.org/)
Maybe I can build my own libicudata.so.