Here is the full list of all 12 SubaraCity trophies - there are 7 bronze, 4 silver and 1 gold.
Unlocked over 15 characters
City reached the highest level, Dragon Class
Unlocked 15 buildings over Lv.10
Made a block of Lv.25 and above
Unlocked 10 buildings over Lv.10
Created a city ranked Eagle Class and above
Built a city for the first time
Unlocked 5 buildings over Lv.10
Over 300 years passed
Unlocked 5 characters
Created a population over 3 million
Created a block of Lv.15 and above