Looking for novels where MC or ML is a teasing flirt! Just like in PUBG : AWM, ML is a "hooligan " and MC is always blushing. That kind of couple!
Transmigrating Into The Heartthrob’s Cannon Fodder Childhood Friend maybe? I don’t know if it exactly fits your requirement. I would give it a try though, it’s a hidden gem!
Restricted Area : the flirting, sexual tension is really good. Though none of them comes in shy person category. Both the ml and mc are proactive.
“I’m completely clueless about sock puppet accounts being unmasked”? The MC is a huge flirt and ML suffers for a bit but halfway through the tides turn and the MC ends up blushing more. It’s also really cute. “I can do it” has tidbits of teasing and lots of blushing from the MC. More comedic tho cute, prep for secondhand embarrassment. “FOG” is a bit angsty during the first 20 or so chapters but the fluff afterwards is adorable and the ML is very shameless and loves to tease while the MC is pretty thin skinned. Fades to dark but not too dark.