Here is the full list of all 30 Valthirian Arc: Hero School Story achievements.
Unite all Five Queendoms.
Finish Chapter 4.
Promote a student to Harlequin.
Promote a student to Paladin.
Promote a student to Scholarsage.
Finish Chapter 3.
Promote a student to Arquebusier.
Enroll 30 new students.
Craft 10 accessories.
Promote a student to Medica.
Promote a student to Arc Draconus.
Craft 10 weapons.
Finish Chapter 2.
Finish 30 errand missions.
Buy an item from the wandering merchant.
Graduate a student.
Finish Chapter 1.
No fallen students for 5 consecutive missions.
Rename a student.
Graduate 50 students.
Obtain Valthir.
Obtain Crescent Edge.
Obtain Shermanstaff.
Reach Accreditation level A.
All facilities built at Accreditation level A.
Ascend Isabel to Mother Seat.
Support one Queendom to rule the Realm.
Learn an ultimate skill.
Have 1,000,000 G in your Academy's funds.
Unlock all achievements.