For a visitor visa, the supporting documents should show that you're tourist. Showing enough funds serves a dual purpose: it makes it likely that you can afford to be a tourist, and also that you have a good job (i.e. less likely that you're looking for a new job in Japan).
Since the typical tourist would not include their father's tax records, adding it would make your application stand out. That is not a good thing. It suggests that you think your application is not strong enough on its own merits. And if you yourself aren't convinced, then why should Japan be convinced?
For the same reason, a letter of guarantee is not as good as some people believe. If you're rich enough yourself, it's not needed. And if not, then is that person perhaps trying to find a better-paying job in the destination country? But for the case of Japan, see Guarantor's role in Japan's short term visa It's not so much a financial guarantee but more of a sworn statement. In your case, your friends statement will make your tourist intent more believable.