If you're spending most of your time in Osaka or Tokyo, traveling to Kanazawa can be a bit of a hike. Although the Hokuriku Shinkansen now connects Tokyo to Kanazawa, the rest of the bullet train route to Kyoto and Osaka is still in the preparation stage, and the distance and cost from either side is pretty significant: A one-way trip between Osaka and Kanazawa would normally take about 2 hours and 45 minutes and cost ¥7,130 on the Thunderbird limited express; Tokyo to Kanazawa takes just a few minutes more and costs ¥13,920 on the Shinkansen.

While a standard round-trip from Osaka to Tokyo would normally be ¥27,240 (about US$242), trying to do a round-trip that includes Kanazawa would seem to add up to a hefty ¥34,670 (US$308) bill. However, there's a trick that can take a big bite out of that price. All you need is a bit of knowledge of how Japan Rail (JR) works.

When you buy a JR ticket that covers a distance of more than 100 kilometers (62 mi), you can get off and on as many times as you like as long as you don't double back along the same route. Be aware that this does not apply to express fares, however, and the policy also doesn't apply to multi-packs of commuter tickets (回数券・kaisuuken) and in the suburbs of major cities.

Furthermore, the longer the distance you cover, the more the rate is discounted. So rather than buy round-trip tickets, it's most economical to try to string together the longest possible one-way course before doubling back on the same part of track. The result is that the cheapest courses look like a number 6, with a big loop and just a final little spigot where you have to retrace your steps to get home. And to ensure that you can get on and off along the way, the key is to start with a regular fare ticket, not an express ticket for your entire journey.

Time is also on your side. JR tickets are valid for longer the greater the distance you travel: one day for up to 100 kilometers, but two days for up to 200 kilometers (124 mi) and three days for up to 400 kilometers (248 mi), with another day added for each additional 200 kilometers of travel. So you can not only get off the train partway along your 100-kilometer-plus trip, but you may not have to get on again for several days. Just don't lose your ticket in your travels!

The upshot is that, with a single, long-loop ticket, you can start in Osaka, spend several days in Tokyo, swing back through Kanazawa, and only spend pocket change on the extra leg of the trip.

The final key is to make sure that last leg where you double back is as short as possible. Assuming you're starting in Osaka, aim to make that the segment between Osaka and Yamashina Station, which is in Kyoto right by the border with Shiga Prefecture.

So how exactly do you make this work? You need the following:

1. A basic fare ticket (乗車券・joshaken) from JR's Osaka city lines (大阪市内・Osaka-shinai) to Yamashina (山科) (¥14,150)

Why the huge price tag for what's normally an ¥840 fare? Because when you buy this ticket, you will select the following intermediate stations: Shin-Osaka, Tokyo and Kanazawa. However, with a distance of over 1,200 kilometers (746 mi), your ticket now has seven days of validity!

2. A Shinkansen express fare ticket (新幹線特急券・Shinkansen tokkyuuken) from Shin-Osaka to Tokyo (¥4,870)

This lets you take the bullet train from Shin-Osaka to Tokyo. If you bought both the express fare and basic fare for this distance together, it would normally be ¥13,620, but the basic fare is already covered by the fare ticket (1) above. However, since this is an express fare, you now can't get off the train anywhere between those two points. Also remember that you can't double back on your route, so while in Tokyo, be sure to use new, separate tickets or an IC card to travel around.

3. A Shinkansen express fare ticket from Tokyo to Kanazawa (¥6,580).

This lets you take the bullet train from Tokyo to Kanazawa, presumably after you've spent some time in Tokyo. Your long basic fare ticket from (1) will now let you get off at Kanazawa as well!

4. An express fare ticket (特急券・tokkyuuken) from Kanazawa to Osaka.

This is normally ¥2,380. However, JR has a policy where if you transfer from the Shinkansen to an express train at certain stations, you can get the express fare at half price: in this case, ¥1,190. Be sure to secure the express ticket before getting on the train or the discount won't apply. The discount is only available on the same day, so you have to get going from Tokyo early to have a reasonable amount of time in Kanazawa before heading back to Osaka. However, if you go the other way from Yamashina and go to Kanazawa before Tokyo, thus transferring from express to Shinkansen, the discount can actually be applied up to a day later—allowing you to spend the night in Kanazawa!

5. A consecutive fare ticket (連続乗車券・rennzoku joshaken) from Yamashina to Osaka (¥840).

This is the only leg of the journey that can't be covered by the initial basic fare ticket in (1). Since it's just 48 kilometers (30 mi), you can't just buy a regular ticket and still have it valid on the final day of your tour. There's an easy fix, though: when you buy the first basic fare ticket, buy this ticket as a "consecutive fare ticket," and it will have the same validity period as the rest of your trip.

The result of all this wand-waving is that your total fare comes to ¥27,630 (US$245)—which is ¥7,040 (US$62) less than you'd pay to buy tickets to each destination individually, and only ¥390 (US$3.46) more than the ¥27,240 you'd pay for a basic round-trip from Shin-Osaka to Tokyo and back.

That said, there are lots of ways to mess this up, so care must be taken. It's best to go to the JR ticket office to get it sorted—and yes, they not only know about this system, they've got illustrated diagrams on their official ticket rules page.

So what have you got to lose? The next time you're traveling between Osaka and Tokyo, put Kanazawa on your list!