Lynch is lying 78th, Liam Glynn is 35th and Ewan McMahon is 81st from 158 boats. Results are here.
The event is the second qualification opportunity for the Tokyo Olympics next year where five places are on offer among 44 countries.
The Carlow sailor has been in exceptional form at most of his major events this year but was cautious on the starting line for both races today and ended up finishing outside the top 20 for the first day.
However, Howth's (Co. Dublin) Ewan McMahon placed third in his first race of the series that is also his first senior world championship. But he was disqualified in the second race for early starting and will endeavour to drop that score under the discard system later in the regatta.
Liam Glynn of Bangor, Co. Down made good on his pre-event training form by placing in the top ten leading boats in both of his races at the first mark before slipping down the ranks by the finish.
The championship series comprises qualification races until Saturday when the 150+ fleet is split into Gold, Silver and Bronze divisions. Ireland needs a finisher in the top five unqualified nations that will certainly be drawn from the upper ranks of the Gold fleet.
"Finn has everything he needs to perform but must look beyond the pressure of the event for the remaining races," commented Vasilij Zgobar, the Slovenian triple Olympic medallist who is the Irish squad head Laser coach. "But I am very pleased with how the younger sailors did on their first day competing at this level."
Racing continues at Sakaiminato-City, Japan on Friday starting at 0300 (Irish Time). The women's Olympic qualifier/Laser Radial World Championship begins in two weeks time at the same venue.