I’m here どこにいたって call me ひとつになれる
I’m here / no matter where you are call me / we’ll become one
Vocabulary & Grammar Notes
Once again, “ni” shows that the word preceding it modifies the verb after it. “Doko” is Japanese for “where.” Japanese: どこ, 何処 (not often seen as kanji in regular writing)
Here, this is a form of the verb “iru” (Japanese: いる、居る), which is the “existence/ presence” verb for animate objects, i.e. people or animal.
Rather than dwell on verb details, here’s the bottom line: using -tte here is using it as an intensifier, to make the verb stronger in a colloquial manner. This is a common enough feature of informal speech.
That is why I have rendered it as “no matter where you are.” After all, the sentence doesn’t define the listener as being anywhere in particular; she could be anywhere, but no matter where that person is, the singer’s “I’m here” will remain true. It’s simple extrapolation.
Hitotsu ni Nareru
Let’s cover this as one phrase.
Here, “hitotsu” means one, as in, becoming one. “Ni” fulfills the same role as before.
“Naru” is “To Become,” and the kanji for it is identified with growth. Thus, something “grows into” something else rather than presto, wave of a magic wand, it has transformed into something else. That’s a different word. Japanese: なる、成る
So, “nareru” is a potential form of “naru.” This is different from conditional forms in this way:
Conditional: If we become one, X will happen
Potential: If X happens, we will become one
Clearly, this phrase is written in the latter manner. Thus: Call me -> as a result, we will become one.