On Nov 21, 増井 慎二郎 submitted the Change Report to Ministry of Finance. The report shows that 増井 慎二郎 decreased their holdings in $OpenWork (5139.JP)$, with their joint shareholding ratio down from 18.98% to 18.97%.
Source: Edinet Announcement
What is the 5% shareholding reporting system?
Shareholders with holding ratio exceeding 5% must submit a Large Shareholding Report within five business days from that day. If the holding ratio increases or decreases by 1% or more after submitting a Large Shareholding Report, the holder must submit a Change Report within five business days from that day.