human
Subaru:  Efficiency was calculated by comparing the usage cost to power, but he had no idea how hard it was for Beatrice to say something that was probably incredibly difficult to admit.
gpt
Beatrice:  “Er? You say that, but you hurled huge spells into the Great Rabbit one after another, right? You even let me use your mana, ’cause it’s not like you were sucking it out of me.”
human
Subaru:  “Was that mana not what Betty stored away over a long period of time, I wonder? Draining Subaru thousands and thousands of times would not be sufficient to suddenly use that much mana in our first battle.”
gpt
Subaru:  “That figures. Incidentally, by stored over a long period of time, you mean…”
human
Beatrice:  “…I—I suppose I was helping myself to mana from everyone at the mansion a little at a time.” Beatrice was red-faced as she divulged the information, perhaps embarrassing from a spirit’s point of view.
gpt
Subaru:  Subaru didn’t have a very clear idea at how unladylike using some kind of mana drain was. “Beako, it seems like you’ve done some deep reflection about it, so I won’t poke fun at you. Well, as your contractor, I’ll just have to put up with whatever you’re going to take from me. How much is stored in this vault anyway?” It hardly needed to be said that Subaru’s mana capacity was lower than that of the average person. If he was to work around Beatrice’s poor fuel efficiency, he needed to break down how to make good use of what had been stored to date. Naturally, he had to get an idea of just how much magic energy was left, but—
human
Beatrice:  “—Nothing.”
gpt
Subaru:  “…Hmm?”
human
Beatrice:  “Did I not say nothing, I wonder? What was stored across four centuries flew out the door during our first battle. Though I still held on to a majority of it despite the loss of the archive, the Al Shamak that served as the finishing blow…might have depleted it completely, I suppose.”
gpt
Subaru:  “” Beatrice’s explanation left Subaru silent. He sank into thought. After pondering the matter, he arrived at an answer. In other words, it went something like this. Beatrice’s stored mana was zero. It would take all of Subaru’s mana just to keep her corporeal on a day-to-day basis. Beatrice could not employ fuel-inefficient high-powered spells, and his pact with her left him unable to rely upon other spirits.
human
Subaru:  “You’re telling me…a duo between a spirit who can’t use magic and a spirit mage who can’t use magic has just been born? !”
gpt
Beatrice:  “W-well, I suppose you could put it in those terms.”
human
Subaru:  “How else would you put it?! Eh? No way—you’re serious? !” In conclusion, Subaru had become a spirit mage, winning the hand of a little girl—and that was pretty much it.
gpt
Beatrice:  “Should I say, Eh-heh-heh, thbbt, I wonder?”
human
Subaru:  “I’m not laughing!” And that was how an incredibly ill-prepared team of spirit mage and spirit was born.