As well as Mr. Yen Japan also has Mr. JGB. Says one day the BOJ will step back from buying

Bloomberg citing head of the department that oversees debt issuance at Japan's Ministry of Finance. Michio Sato, dubbed Mr. JGB.

• Investors should start preparing for a return to normal Japanese bond trading as the central bank will one day step back from its debt purchases
• Ministry of Finance has already started looking into a comprehensive review to ensure there’s sufficient depth and liquidity in the market

As for timing, he really isn't much help:

“I don’t know when exactly, but the time will eventually come when the central bank is no longer the main buyer of JGBs,”

---

the Bank of Japan currently holds around half of JGBs that are outstanding. And are still buying.

Here is the link to Bloomberg for more.