Question regarding Dragon Sakai

[EK Dynomite]

If Maya talks about him once, will you always have the chance? That's what i've heard but I just want to make sure.

[Isolde]

If Maya talks about him once, will you always have the chance? That's what i've heard but I just want to make sure.

Once he is mentioned, you will always have the chance of getting a 'Block ???' where you will encounter him and receive a Dragon Scale in a present. BUT, you have to do the mission on A rank to get the Dragon Scale. Once you encounter him and receive the Dragon Scale present, you can abandon the mission. You can only receive the Dragon Scale (up to) once per mission.