Sorry for jumping into the conversation midway through, but as someone who does translation for a living, this is a rather interesting topic for me. (Apologies in advance if what I'm about to say is a bit "meta".)
Well...not necessarily.
Most professional translators will agree that the ideal translation is one that evokes the same feelings/imagery in the target language as the original work did in the source language, not necessarily one that strictly adheres closest to the literal wording or structure of the original. (As a translator, perhaps you already agree with this.)
So what does that mean in this case? In my experience, Japanese tends to play a bit more free and loose with tense than English does, and this includes this sort of use of the "historical present." It's not impossible to narrate past events in the present in English, and you see it sometimes, but generally it will be for an extended passage (like a story within a story) or a stylistic choice carried out for the entire work. Jumping from past to present tense for a sentence or two is something you see a lot more in Japanese than in English. (Sorry, these are the only two languages I'm qualified to comment on, given my nonexistent ability in all others.)
This means that if one were to strictly preserve tense here in an English translation, there's a chance that it would come out as far more disjointed and jarring than the author originally intended (and by extension, than native Japanese speakers would feel when reading the original work). As the translator, you have to make a judgment call for yourself whether translating a given sentence or sentences in the present would serve to better allowing your readers in to hear the author's original voice, or whether they would actually hinder the reader's experience by introducing something that may feel natural in Japanese, but come off as disjointed and unusual in Portuguese.
Unfortunately, translation isn't an exact science, so there's not really one "right" answer. Then again, that's also what can make translation an interesting and rewarding craft. (At least, I think it is.
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