The 21-year-old Thai No 5 won a nail-biting opener 21-19 but then lost her touch to go down 21-15 21-14 against the 101st-ranked player after 62 minutes of play.
Shizuka, who received a first-round walkover after Thailand’s world No 2 Ratchanok Inthanon withdrew with a back injury, levelled her career record against Porntip after the Thai beat her 21-19 11-21 17-21 in the Osaka International tournament three years ago.
In the men’s singles second round, Thai No 2 Tanongsak Saensomboonsuk was outclassed by Chinese Huan Gao, who surged to a 21-13 21-5 win in just 36 minutes.