DeviL303 has just found that it was possible to gain storage space in the dev_flash partition by deleting unusable files and that will not jeopardize its operation. So he produced a PKG that will take care of removing particular Japanese characters, files like hknw_plugin.sprx or hknw_plugin.rco and some images from the photo gallery.
It is possible to gain 18 MB by running Minus_18MB.PKG