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(Warning: some of these contain dark themes/images)
Mushishi (fantastic story telling and unique premise, I highly recommend watching the anime as well since it has a beautiful soundtrack and stunning visuals)
Heaven's Design Team (fun, cute, and you learn about different animals, + there's an anime adaptation if you're interested)
Three Days of Happiness (engaging story and interesting relationships and perspectives on life)
Kiichi!! (interesting story and gives the reader a lot to think about in terms of society and it's effects on different people)
Kiichi VS (sequel to the previous one)
Sunny (MATSUMOTO Taiyou) (unique art and story telling that focuses on how different kids process/view/deal with their situation in life)
Oyasumi Punpun (dark, interesting, and wonderful art)
To You, The Immortal (fascinating perspectives on life, death, and humanity throughout the ages, there's also an anime adaptation if you're interested)
Hikaru ga Shinda Natsu (great story, great art, interesting plot)
Kamonohashi Ron no Kindan Suiri (the mystery element keeps you engaged and guessing, very fun, there's an anime adaptation if you're interested)
Monster (incredible story overall, this one also has an anime adaptation if you're interested)
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I'm sorry for the late reply, here is the link :
https://mentoltrans.wordpress.com/the-hunters-gonna-lay-low/
I hope it'll suit your tastes !!
Does anyone have any suggestions? I'm looking for manga which makes me feel like I'm doing something productive for once or one that'll suck my boredom right out of me. Something engaging and meaningful is what I'm looking for. I'm grateful for any suggestions.