The 28th being a Tuesday, and the game against the Fighters, I really would doubt you'd have any problem getting a ticket after your arrival. In fact, I would be pretty sure you could get tickets at the stadium, provided you do not have a specific request for the seats.

Tickets are not on sale yet.

The tickets are available everywhere, Ticket PIA counters are a good bet and you also have various ticketing machines at convenience stores like Lawson, but yes, the language could be a problem, so jib71's suggestion of writing down your request is useful. Is there a concierge at your hotel who could book or at least write it down in Japanese for you? If you know in which area you will stay I could check the nearest counter for buying them.