Assuming Willpower 10, Integrity 5, Essence 3 (i.e. the maximum a god-blooded can get without becoming a spirit), he has a Dodge MDV of 9. We'll also give him an Appearance of 3 (attractive, but not especially so).
I'll use Amu's social stats with the modification of Presence 4 (necessary for ISS) and Socialize 2 (necessary for Mastery of Small Manners), and the addition of First Presence Excellency, Irresistible Salesman Spirit, Enemy Castigating Solar Judgement, and Mastery of Small Manners.
Amu makes a social attack where she attempts to make Hotsuin feel guilty for not spreading the Nicaea program to provide protection for emergency services. She gets a 2-die stunt (for the sake of argument; it's generally pretty easy, assuming the ST is using the guidelines from the book). She spends 6m on First Presence Excellency, 3m on Irresistible Salesman Spirit, 2m on Enemy Castigating Solar Judgement, and 1m on Mastery of Small Manners (total 12m spent). This gives her a dice pool of 16 dice, and we'll assume the roll is average, giving her 8 successes; this is promptly doubled to 16. Her Appearance of 4 (3 natural, +1 from MoSM) reduces Hotsuin's DMDV to 8. ECSJ cuts that in half to 4 (because this is a social attack attempting to create guilt). This gives Amu 12 threshold successes on her attack.
For every 3 full successes above the target's MDV, they must spend an additional 1 wp to resist. That single attack just drained half of Hotsuin's Willpower (1 + (12/3) = 1 + 4 = 5).
This is ignoring how playing to/against his Motivation, Intimacies, Virtues, etc., would change his MDV, because it's not really important to my point (ultimately, it's perhaps +1 to his MDV before halving): a Solar is completely capable of smashing a mortal in an area where they have invested themselves.
We have not invested in social combat, so we cannot do this yet. I realize this.
