Gosh. Social media for Grassblades-folks? Let's see what we can come up with....
Masahiro would be that guy who has NO social media presence. Heck, he doesn't even have an email-address. He's a digital ghost.
At most, he has a smartphone he never uses. Akane's somehow installed Instagram on it and keeps posting pictures of funny rocks, weird frogs and shiny things she finds. Sometimes, Masahiro's in the background, blurry and grumpy as heck.
Chouko would have a twitter account, but it would be more informative than personal. She'd RT political news and interesting science facts, and use it to keep tabs on her social circle. She'd also be running a chat-group somewhere, probably Discord or Slack, to keep everyone who works with her in the loop on important things.
Dateh would have an Instagram, where he'd post lots of pictures of food and fluffy animals and flowers and things, and a Twitter to be sociable on, and maybe tweet short poems. Kazue would have a Twitter and an Instagram, and maybe a themed Tumblr-blog or two. She'd be the one getting into screaming-matches with morons on the internet and Tweeting long, threaded rants at 1am. Her Instagram would be 50% cool and funny things that caught her eye, 50% selfies and pictures of her friends. Her Tumblr-blog would be all about celebrating cool ladies in stylish clothes that she herself would never ever wear. Also, a Vine-account posting jokey videos that are genuinely funny 45% of the time, and fall absolutely flat for the remaining 55%.
Lady Watanabe would have the snarkiest Twitter-account on the internet. People would think it was a parody account, but it's her. Her sidekick Ying would have a Tumblr-blog full of thought-provoking philosophical articles and the occasional cool picture with a poetry-quote in Helvetica across it. Would occasionally reblog tearjerker GIF-sets of popular movies. They'd be co-creators of a blog dedicated to those weird speculative fiction text-posts you see rolling by on Tumblr sometimes - the Earth-is-space-Australia, and what-would-real-urban-magic-be-like and stuff like that.
Wen would be the one getting into fights with Kazue on Twitter, and would 100% have a personal Tumblr shouting angrily about social justice, arguing with anons and occasionally reblogging photos of historical weaponry. ... and then she'd have a super-secret Twitter-account where she tweeted about personal feelings. It would have zero followers. Kobayashi would have a Twitter-account trying to sound like a serious statesman, but he won't have figured out how to cope with the 140-character limit and would keep messing it up. Wen would loyally RT anything she found particular inspirational there. Kobayashi also has a Google+ account he never uses, and a Myspace, because nobody told him Myspace is dead, and he doesn't get social media anyway.
Tessai (who has not yet been named in the comic) would have a Twitter account and would tweet annoying jokes at Wen just to rile her up.
The Stranger Things-boys would each have an Instagram. Yarrow's would be all about baking and tea and gardening and self-care tips and pictures of his unimpressed cat. Isam's would be attempts at serious artistic photography and he'd actually be kinda decent at it, mixed in with pictures of stuff he's eating and maybe a cute animal or two he spotted. Also, pictures of his friends, but none of himself.
.... I just had way too much fun writing this post. XD