Baseball Tickets 04/16 Swallows vs Giants

I'd like to see a baseball game, and the game on 04/16 in Jingu Stadium seems the best oportunity I have.

Do you think I can still buy a ticket when I show up at the stadium at the time of the game or is it better to buy it in advance?

I'm not sure because I read that the Giants are very popular. In fact I'm not sure because of the weather and because of my travel plans, and buying a ticket in advance via japanball.com costs a fee of $59 additional to the ticket price.

It's available a Day ticket if you don't mind that your seat is either Giants or Swallows side with an outside reserved(a little expensive for 2,000 YEN(1,600 YEN for unreserved seat)).
I guess outside unreserved seats are probably available on the game day(not sure).

Thank you for your advice. I'm not so familiar with baseball. How good / bad are the unreserved outside seats? And is there a difference for a foreigner like me if the seat is on the Giants or on the Swallows side? Are there more cheers or something like that on the side of the home team that makes the one side better than the other?

Giants - Swallows are rivalry for long term. Both teams are based in Tokyo(Jingu stadium is Swallows home stadium), fans are completely separated(never mix).
If you are a Swallows fan, you can't sit on Giants side(visitors side). Swallows fan never sit on the visitors side.
If you like to enjoy how Japanese baseball is like, it is no problem you sit on either the side but you must support the team you sat on.

Un-reserves seats are available first-come first-served basis. Some fans wait for hours to get a good seat on un-reserved side.
Reserved seats are secured seats for you. You need to show the ticket to the officials to enter the seat area. If you go to toilet, it's out of the area, so you need to show the ticket to go back to your seat each time.

I think you can enjoy on Swallows side(Home side) if you have chance to visit Jingu stadium. If you visit Tokyo Dome, then choose Giants side(home side).

Jingu stadium has no roof or cover, so if it it forecast heavy rain, the game is cancelled(little rain is still on). Tokyo Dome has a cover.

Thank you for your helpful information!

So it seems each side is good for me, but maybe it's better to buy at ticket in advance, so I can get a good seat.

Thank you!