Learning Spanish in Japanese

In college I was learning French, Japanese, and Russian all at once. Alas, my French has devolved to barely passable and my Russian is pretty much nonexistent, although I can still read Cyrillic--Cyrillic, my love. Anyways, I don't recall actually studying any of them VIA the other one. While I was living in Paris, I had started sort of doing Russian via French (at the Sorbonne, but also from some books on my own) although most of the time it was Russian and French simultaneously via English, since I was advanced enough in my Russian (though not technically considered "advanced" by any means) that at least vocab-wise it was keeping pretty good pace with French at that point.

It has been suggested recently that I take up Spanish, and my thoughts have always gone in this direction considering I am a minority in my Latino neighborhood. I mean, I feel silly NOT speaking Spanish. This morning they took an interesting turn when I realized that I would be starting not entirely from scratch (I took some Spanish in middle/high school), but I'd need to refresh everything regardless, so I might as well be. What it seems like is a really great opportunity to exercise...my Japanese?

If I'm learning basic Spanish then they should all be things I know in Japanese, and if there are things I DON'T Know in Japanese that I come across in a beginner's Spanish textbook, then I should LEARN them, ASAP. I'm almost tempted to buy a Japanese Spanish textbook, but for a variety of reasons I see that not turning out very well. No, I'd have to make my own awkward pb and mint jelly (They don't go together do they?) sandwich, but it might be worth doing...

Really, though, I would rather get back to French or Russian lol

INCORRIGIBLE, that's what I am, and maybe just stubborn. Here I am immersed in Spanish and not paying attention to a word of it... (Ok, maybe a word or two, but no more...)