WITH a AS
(
SELECT 'K1' gubun FROM dual
UNION ALL SELECT 'K2' FROM dual
UNION ALL SELECT 'S1' FROM dual
UNION ALL SELECT 'S1' FROM dual
UNION ALL SELECT 'S2' FROM dual
)
, b AS
(
SELECT 'K1' kind FROM dual
UNION ALL SELECT 'K1' FROM dual
UNION ALL SELECT 'K2' FROM dual
UNION ALL SELECT 'S1' FROM dual
UNION ALL SELECT 'S2' FROM dual
)
, c AS
(
SELECT 'K1' sect FROM dual
UNION ALL SELECT 'K2' FROM dual
UNION ALL SELECT 'S1' FROM dual
UNION ALL SELECT 'S2' FROM dual
UNION ALL SELECT 'S1' FROM dual
)
, d AS
(
SELECT 'K1' gubun FROM dual
UNION ALL SELECT 'K1' FROM dual
UNION ALL SELECT 'K2' FROM dual
UNION ALL SELECT 'K2' FROM dual
UNION ALL SELECT 'S2' FROM dual
)
SELECT SUBSTR(
       REGEXP_REPLACE(',A,B,C,D'
       , LISTAGG(','||tb, '|') WITHIN GROUP(ORDER BY tb)
       ), 2) tb
     , v
  FROM (SELECT 'A' tb, gubun v FROM a
        UNION SELECT 'B', kind FROM b
        UNION SELECT 'C', sect FROM c
        UNION SELECT 'D', gubun FROM d
        ) x
 GROUP BY v
 HAVING COUNT(*) < 4
;