Aiful Corp, one of the larger firms in the sector, has indicated that it might sue over being branded as "arguably insolvent".
This statement was originally contained in a report from Walter Altherr, an analyst for the investment bank - and his employers have now suspended their coverage of the market, as well as withdrawing past research on the firm.
"All previous ratings and forecasts should no longer be relied upon," a spokesperson confirmed.
Aiful - which says that it is still considering the legal action despite these conciliatory gestures - has faced a drop in the value of its stock of 35 per cent since the comments were originally made on June 23rd.
Tokyo-based asset manager Hiroyoshi Nakagawa told Bloomberg that Lehman's move was a sign that the bank "admits its error" in making the report.
"[It] could have a negative impact on the reputation of its research section,'' he added.