Here is the full list of all 43 Millennium 4 - there are Beyond Sunset achievements.
Complete 1 quest
Kill Golem Overking
Get 50+ Gold from a gold sack
Reach lvl 6 in Bare Hands with Benoit
Play 1+ hour
Complete 6+ quests
150+ items found
Find 1 secret room
Find 5+ secret rooms
20+ secret rooms found
All secret rooms found
Complete the game fully (all quests, secret rooms and animal kings)
Kill all animal kings
Hard Mode Completed
Held more than 99,000 Gold
All quests completed
Finish the game in less than 13 hours in Hard Mode
Spend 40+ hours on the game
1000+ fights
Kill Gorilla Lord
Kill Legendary Warrior
Kill Kingdom of Weapons
Kill Soil of War
Kill Shooking
Kill Urchin Nation
Kill Perfect Chopper
Kill the King
Register Old Suzuki (just in time!)
Convince the Bear to join
Go through the Grand Rift
Pass the Crystals trial
Kill 15+ groups of Tianas during the second trial
Defeat the Tyranosaurus
Recruit Wolfgang
400+ hits with Marine's hands
600+ hits with Salome's Hands
3+ hits with James' Hands
99+ hits with Bokden's Hands
Recruit Bokden
Kill more than 1000 enemies with Bokden
Complete Q9 (Find Jacque's Hair Potion)
Find 40+ XP baskets
Kill 1000+ enemies with The Bear