A minor correction to the kanji from what appears to be broadcast recordings of the OP with lyrics on screen, that I bring up here because it seems the original poster has been inactive since 2008.


Lyrics link:

https://www.animelyrics.com/anime/ry.../heartwave.htm


YouTube link to what seems to be a broadcast recording of the OP:




The line 同じ周端数　重ね合い君と話すshould read 同じ周波数　重ね合い君と話す


周波数 refers to frequency, a common theme for a series involving radio waves. Given that the above video appears to be a broadcast recording with 波 rather than 端, I don't think there's a pun happening here.