To improve your jutsus you need special jutsu books.
To improve your jutsu you need to use a jutsu book on yourself (you have a 40% chance to improve). To get your jutsu upgraded, you need to upgrade up it 10 times.
An unknown jutsu book can be obtained mainly from shinobi statues but also from quests, events and for immortal points and war village points
Unknown jutsu book must be identified by libralian (you must have 1 rare green pebble) then receive a random jutsu book.
Upgraded jutsus have upraded or additional abilities