Here is a list i wrote up about the changes the natures do to the stats.
Natures
- Brave ~ STR++, AGI+, CHM-
- Hotblooded ~ STR++, CON+
- Pure ~ CON-, AGI+, DEX++
- Childlike ~ DMP+, AGI-, CHM++
- Wise ~ DP+, DMP++, DEX-
- Nihilistic ~ STR-, AGI+
- Reckless ~ HP-, STR++, CON+
- Stickler ~ DP-, DMP++, DEX+
- Zealous ~ DMP-, AGI++, CHM+
- Pouty ~ DP++, CON+
- Stubborn ~ HP+, CON++, AGI-
- Fickle ~ HP-, DP++
- Cheerful ~ STR-, CHM+
- Happy ~ CON++, DMP-, DEX+
- Passionate ~ STR+, DEX-, CHM++
- Optimistic ~ CON-, AGI++, CHM-
- Arrogant ~ HP++, DP-, STR+
- Determined ~ HP-, DMP+, CHM++
- Selfish ~ CON++, AGI-, DEX+
- Earnest ~ HP+, DP-, DMP++
- Precise ~ STR-, DEX++
- Kind ~ HP++, DP+
- Neurotic ~ HP++, STR+, CHM-
- Reliable ~ HP+, CON++, DEX-
- Loner ~ CON-, DMP+, AGI++
- Gloomy ~ DP+, DMP-, DEX++
- Rational ~ HP-, AGI++
- Egotistical ~ DP+, STR++
- Mischievous ~ HP+, DP-, DEX++, CHM-
- Perverted ~ CHM SUPER+ (100%)
- Average ~ Changes nothing
- Lucky ~ Cuts STR, CON, DMP, AGI, DEX and CHM in half. Presumably makes Luck skyrocket.
Explanations
I tested this all out on a Aster Knight which has 100% in everything.
Each – or + is 5%. It varies depending on if the puppet class already has above or below 100%. For example, Theatical Star has 125% in AGI, if we use AGI+ to that it becomes 131% and AGI++ becomes 137%. Where as if we take 75% in HP and use HP- it only becomes 71% or if we use HP+ it only becomes 78%. If you use perverted nature on Theatical Star which has 125% in CHM it becomes 250%. So its not 5 flat amount, its 5% of whatever the base number is.
Does that make any sense? I’m not good at putting my thoughts into writing.
Also you may see some natures that you cant pick when making a puppet thats because to get them as a book you use use on your puppet which you can buy at the shop or are unlocked by a petition a bit later in the game. That being said there might be more that i have not seen yet (post game stuff?)