Regalia: Of Men and Monarchs - Royal Edition (EP)

Missable: Esther is only available if you side with Shendu in the diplomatic conflict between them and Lordemar. So you can either have Esther or Henrietta.
To get both characters achievements done as fast as possible wait for around the middle of chapter 3. Then you should have at least 3 diplomatic choices in the conflicts between Alfheimr(Valen) vs The Empire(Mifune) and Shendu(Esther) vs Lordemar(Henrietta).
Make a save at that point and be sure to keep it. Then do 3 choices for one side in each conflict (at the desk in your castle), shortly after that these kingdoms exclusive character will arrive. Then work on maxing these characters bonds to get their respective achievements.
After that reload your previous save making the opposite choices to get the achievements for the other characters. You can then decide which characters you like more and to continue with but it isn't important for anything else which you pick. Also the decisions in the conflicts seem to have no further consequences.

This achievement is for maxing Esther 's personal bond.

You must achieve stage 5 bonding with the person to get this achievement.

Bonding is mostly done spending time with a character.
A bit can be achieved during text adventures and camps but that doesn't make much difference.
On the map some characters will have a heart icon so with these characters you can work on your bonding by spending the day with them. You can also press "Y" to see the weekdays on which you can do bonding with each character but as you will need to work on all anyway I would simply work on another character when the one you want to max is not available on the current day.

When spending the day with the character you will normally have a conversation where you can typically two times choose between 3 answers. Can also be less time or more sometimes even none.
For most cases one of the answers makes no difference, one gives a good result which is one arrow up and one gives a great result with three arrows up. Which the best answer is depends on the personality of the character so I would advice to save when in the characters location and reload if you don't at least get three arrows up once.

Esther is a bold machinist she likes to be treated like a good buddy so you can make fun with her and be a bit more rough.
So for her it isn't that easy to always pick the best answer.

At some point normally around stage 3 for most characters there will be a bonding quest where you need to travel to a smaller location on the map and finish a conversation battle or text adventure to go on with the bonding for that character. Simply finish that and you can continue with the binding. There is an overview in the menues for each character where you can see the current bonding status and it will also state if you need to finish a bonding quest to continue.
Also for townsfolk like the smith it is necessary to upgrade their location to progress with the bonding.

It's quite a pain as loading times are quite long and you need to do bonding with almost all characters to get all the related achievements.
Bonding achievements are not missable as you can continue with them after the end of the story.
There only are 4 exclusive characters of which you can only have 2 depending on your diplomatic choices.