The yen's status as a haven currency is helping it to suck in investors seeking shelter from the euro-zone maelstrom.
Last week, the Japanese currency appreciated for a fourth week against the euro after the failure of Greek politicians to form a government raised worries about an escalation of the crisis.
The currency climbed 2.2 per cent against the euro, with the euro weakening to ¥100.98.
The yen also rose to a three-month high against the US dollar.
In fact, the currency stands out as a star performer among all of its major counterparts. Across the year, it has gained 9.2 per cent, more than any other of the 10 developed-nation currencies tracked by Bloomberg correlation-weighted indexes.
The dollar has surged 7.3 per cent, while the euro has lost 4.3 per cent.
"The global market remains nervous," Kikuko Takeda, a senior currency economist based in London at Bank of Tokyo Mitsubishi, was quoted as saying by the news website ekathimerini.com last week.
"We can't buy the euro, and if the US economic outlook is uncertain, yen will be bought."
But the currency's surge is being watched with a beady eye by policymakers in Tokyo.
A high currency threatens Japanese exporters, only recently recovering after last year's earthquake and tsunami derailed the country's export-led model.
"We are watching currencies with a heightened sense of caution and are prepared to respond as appropriate," Jun Azumithe, the Japanese finance minister, was quoted as saying by Reuters on Thursday.
A record ¥8 trillion was pumped into the currency market last October after the dollar reached a record low of ¥75.31.
Authorities have resisted the temptation to step in since then, but analysts speculate that more intervention may be on the cards if the yen continues rising.
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