I'm looking for a manga with a senpai and kouhai couple doujin, the setings was on a beach, characters look for female was a short black hair like ritsu hairstyle and iirc she's wearing glasses and a headband that exposes her forehead and the male characters were usual kouhai look-alike, the story starts here the female character was flirting her kouhai that was aroused by her senpai bikini then she do quick hand job then suddenly there was a gang looking for senpai and both of them surprised and ran into the public toilet then they hide in a shower stall while trying to hide from the gang, oh their position was kouhai holding her senpai to the wall but kouhai was aroused AF and having an erection and kouhai insert his penis into her senpai meanwhile the gang was looking for them kouhai is having sex with senpai and she's moaning making the gang checking their stall but kouhai turn the shower on and the gang leave them, then... story ends.