Bangkok, Aug 9, 2012 (AFP) - Early-starter Kim laid down a marker with nine birdies and a bogey to hold the clubhouse lead at the Suwan Golf and Country Club until late in the afternoon when Yoshida closed with two birdies to match his score.
A shot further back were China's Liang, Australians Nick Cullen and David McKenzie, Taiwan's Chan Shih-chang and Thai amateur Natipong Srithong.
Defending champion Andre Stolz remains in the hunt after firing a two-under 70 around the immaculate 7,077 yard (6,471 metre) course, on the western outskirts of Bangkok.
Joint-leader Kim, 35, credited a small swing change two weeks ago for a big improvement in his performance. 
"I wasn't happy with my swing, so I decided to make a few changes," Kim said. "It was just a slight change to the plane, so now I am getting more of a draw which gives me more distance."
Yoshida, 30, still searching for his first professional win and struggling for regular starts on the Japan Tour, missed only one green in regulation all day -- and chipped in for birdie on that hole anyway.
"My driving was very good and my approach play perfect," he said. "This is only the second time I have been in Thailand, but I like it."
The Thailand Open, the fifth stop on the OneAsia schedule, has seen only two Thai winners in its history despite the Kingdom producing some of the region's best golfers, and it was left to 18-year-old amateur Natipong to fly the flag with a brilliant 65.
"It's my home course but I'm still surprised I played so well," said Natipong, who won a team gold and individual silver medal at the Southeast Asian Games last year. "My best round here before today was a 67."
Prom Meesawat, whose father Suthep was in 1991 the first Thai to lift the title, remains well in the hunt after closing with a 66, the same as big-hitting countryman Kiradech Aphibarnrat.
"I am happy with the way I played," said the man known as the "Big Dolphin" because of his size. "I had one bad shot when I hit in the water, but the wind took it a bit, so I am not too upset."
Prayad Marksaeng, runner-up last year and considered one of the best bets for a home victory, withdrew before the start because of an elbow injury that had plagued him all week.
Liang, winner of the Thailand Open two years ago, credited a new long putter with his return to form.
"It has made a big difference to my game," he said.
The best of a European Tour raiding force on Thursday was Englishman Richard Finch, who was two shots off the lead following an excellent 66.
The record 168-player field will be cut to the top 65 and ties following Friday's second round.
Leading scores Thursday after the first round of the $1 million Thailand Open at Suwan Golf and Country Club:
64 - Kim Hyung-Tae (KOR), Yasunori Yoshida (JPN)
65 - Liang Wenchong (CHN), Nick Cullen (AUS), Chan Shih-chang (TPE), David McKenzie (AUS), Natipong Srithong (am, THA)
66 - Wisut Artjanawat (THA), Nicholas Fung (MAS), Kiradech Aphibarnrat (THA), Richard Finch (ENG), Lee Sang-Hee (KOR), Kim Do-Hoon 753 (KOR), Craig Hancock (AUS), Choi Jin-Ho (KOR), Prom Meesawat (THA), Hwang In-Choon (KOR), Choi Ho-Sung (KOR)
67 - Danny Chia (MAS), Brent McCullough (AUS), Kim Woo-Hyun (KOR), Kim Byung-Jun (KOR), Wu Wei-Huang (CHN), Chris Wood (ENG), Rohan Blizard (AUS), Lee Dong-Hwan (KOR), Arnond Vongvanij (THA)
68 - Su Dong (CHN), Scott Strange (AUS), Jang Dong-Kyu (KOR), Stephen Leaney (AUS), Terry Pilkadaris (AUS), Panuwat Muenlek (THA), Han Ren (CHN), Thaworn Wiratchant (THA), Douglas Holloway (NZL), Poom Saksansin (am, THA)
69 - Danthai Boonma (am, THA), Park Eun-Shin (KOR), Gerald Rosales (PHI), Kim Meen-Whee (KOR), Park Sang-Hyun (KOR), Varut Chomchalam (THA), Simon Yates (SCO), David Brandson (AUS), Koichi Kitamura (JPN), Stephen Dartnall (AUS), Han Min-Kyu (KOR), Park Hyo-Won (KOR), Lee Tae-Hee (KOR), Pavit Tangkamolprasert (THA), Peter Wilson (AUS), Boonchu Ruangkit (THA), Zhang Xinjun (CHN), Huang Wenyi (CHN), Will Yanagisawa (USA), Seo Jeoung-Min (KOR)
70 - Yang Ji-Ho (KOR), Gunn Charoenkul (THA), Scott Arnold (AUS), Udorn Duangdecha (THA), Scott Laycock (AUS), David Horsey (ENG), Andre Stolz (AUS), Chapchai Nirat (THA), Ryan Haller (AUS), Michael Long (NZL), Thanyakon Khrongpha (THA), Mark Brown (NZL), Pawin Ingkhapradit (THA), Lee Jin-Won (KOR), Itthipat Buranatanyarat (am, THA), Lee Dong-Min (KOR), Li Haotong (CHN), Hidemichi Haginomori (JPN), Gareth Paddison (NZL), Chawalit Plaphol (THA), Adam Crawford (AUS), Han Chang-Won (KOR), Lucas Lee (BRA), Michael Wright (AUS), David Howell (ENG), Peter O'Malley (AUS), Choi Joon-Woo (KOR), Kim Felton (AUS), Leigh Deagan (AUS), Park Min-Jun (KOR), Sattaya Supupramai (THA)