Question: Which papers' first author is affiliated with an institution in the country "Japan" and has last name "Ohori"? Give me the titles of the papers.
SQL: SELECT t3.title FROM authors AS t1 JOIN authorship AS t2 ON t1.authid  =  t2.authid JOIN papers AS t3 ON t2.paperid  =  t3.paperid JOIN inst AS t4 ON t2.instid  =  t4.instid WHERE t4.country  =  "Japan" AND t2.authorder  =  1 AND t1.lname  =  "Ohori"