Asdivine Cross

This achievement is for getting the Normal ending of the game with Olivia at max trust.

Here's the step-by-step process for getting all the Normal ending achievements:

1. When you complete Main Quest 88 - World of the Deities in Elysium, make a save before fighting the final boss. You'll need to reload this save to complete the Normal ending with each of the three ladies at max trust and once without anyone at max trust, so a save here is crucial.

There are trust related achievements for the True ending as well, so I recommend using the ending without anyone at max trust for your clear save to go into NG+.

2. You need to increase Olivia's Trust Level to 100 by giving her gifts. Each character gains 20 trust from Four-Leaf Clovers, and Olivia gains 5 trust from Religious Treatises. You can check Olivia's Trust Level on the second page of her status screen.

There are a number of Four-Leaf Clovers in chests throughout the game. I had 4 when I reached this point, which was enough to get any one character to 100 trust.

If you don't have enough gifts to get Olivia to 100, you can buy Four-Leaf Clovers from the premium Shop for 200 ACP each, or you can buy Religious Treatises from the Guild Coin Exchange (the Arena prizes) for 120 Coins each.

3. Defeat the final boss and mash through the cutscenes. There will be an additional scene after the credits, and the achievement will pop once that's done.

Save your clear data in a new save slot. Don't overwrite your save before the final boss with the clear data. If you overwrite your save, you'll need to get more Four-Leaf Clovers

I'm not sure if you can get this achievement in NG+, but if you don't have any saves before completing Elysium, you'll have to start over to be able to get the Normal ending achievements.

Quick Summary:
Four-Leaf Clovers give 20 trust (200 ACP in premium shop)
Religious Treatises give 5 trust (120 Coins in Guild Coin Exchange)
You need Olivia at max trust for this achievement