Weird, I find it difficult to believe that Singaporeans travel to Nagoya, Osaka or Sapporo more often than Tokyo. And how come Kuala Lumpur and Johor Bahru are not on the list? I mean Johor Bahru is literally next to Singapore, you can go shopping or have lunch there and return to Singapore on the same day easily. Maybe they don't consider this as visiting a city then.
The source data is quite clearly incorrect, because Johor Baharu accounts for about as many Singaporean visitors as the rest of the world put together.