Here is the full list of all 20 Sengoku Neet achievements.
Captured all territories.
First child was born
1 Character Lv MAX
Nice strike by Nobunaga
Dispatched 100K soldiers
Dispatched a million soldiers
All woman characters had a child
Completed search of one area
Completed search of all areas
You had a special experience
Total amount of production exceeded 80K
The development level was maximized in all areas.
The Gunner sortie for the first time
The Weapon sortie for the first time
Knocked down Nobunaga within 1 minutes and 30 seconds
Knocked down Perry within 4 minutes
Knocked down Super Giant Ogre within 1 minutes and 30 seconds
Haniwa General become a human
100 children was born
Made the party a male character only