Japanese factory managers' mood improved slightly in May as commodity-related industries recovered from the Iran war-induced sharp drop a month earlier, but weakness in autos and some other industries capped the rebound, the Reuters Tankan poll showed. The monthly poll, a leading indicator of the Bank of Japan's quarterly Tankan business survey, showed manufacturers' sentiment inched up to plus 8 in May from April's plus 7, although it remained well below March's plus 18 that marked a four-year high.