Most of the manga on this list deals with heavy topics, a good part of it is straight-up horror, but this little series hit a soft spot in my heart. Although it would be dishonest to claim this is a simple happy story about a relationship between a parent and child like 'Yotsuba&!', as from the very beginning the facade of a happy fantasy land is questioned. The best way I can explain the tone of this manga is to say its a combination of 'Adventure Time' and 'Moomins'. It is not hard to draw a line between this manga, about the last person on earth who lives with a simply drawn creature who serves as a father figure, to 'Adventure Time'. I would say that the soul of the story lies in the 'Moomins' comparison. Many young kids watching one of the 'Moomins' show were scared by the character of The Groke, a cold and lonely creature seen as a terrifying monster. She actually is simply lonely, she is a tragic character who breaks the coy and comfy feeling of the typical 'Moomins' stories. 'Rojica & Rakkasei' executes similar, often much darker, stories repeatedly. It even features a character that visually resembles The Groke so strongly that I can't help but to believe it is a direct reference. I do think it is a disservice to boil down the manga like his, as every story that breaks the facade of a peaceful green wonderland does so in a unique and engaging way. You never know when or even if a story will take a darker turn. And the stories rarely rely on shock factor for this, every story like this feels deeply human and tragic.
The heart of the series, as is easy to guess from the title, is the paternal relationship between the two protagonists. Rojica is the type of parent who deep down is still a child themselves. He always has to turn towards people he sees as more mature in order to accommodate his adoptive daughter. Before you ever find out how he even found himself in this situation, you already know that he desires to take care of Rakkasei not because of any paternal instinct but because of simple kindness and love towards others. Rakkasei, on the other hand, is a typical child. She is impatient, always wants to play and explore while wearing her 'Vicky the Viking' helmet, and most importantly always wants to do the proper thing when faced with adversity. Not to get too personal, but I am incapable of having children. My dormant maternal instinct gets slightly fulfilled whenever I read a story like this or 'Yotsuba&!'. I am taking you on this slight tangent in order to explain my bias when I say that while Rakkasei is a simple character, she is essential to the story and consistently one of its best features. Which says a lot as I would earnestly say that this manga shines in just about every area.
The art is stunning. The story tackles difficult and significant issues such as environmentalism in an interesting way that I am sure you will not expect. I have avoided discussing a lot of what makes this manga shine, as the sense of mystery about the world is not something I wish to take away from someone who is interested in reading this title.