This is charming whodunnit that immediately reminds me of classical detective novels, but with a personal spin to it. It got all the gameplay elements you'll find in a mystery game: an extensive notebook that keeps track of the characters, and there's a portion where you visit different rooms to interrogate the potential culprits to shake out information from them.
The game is very cohesive and memorable with its style. The art, writing (the way characters talk and the vocabulary used to describe the world), and music are all a perfect fit for the Edwardian setting. I can even find myself humming some of the tunes in this game. The art style is gorgeous with the watercolour and inking where everything including the GUI seems to be custom-made. It's dedication to paint over your own photographs!
All the characters are lovely. I enjoy the diversity in the character designs with poc and varying body sizes. It took some time to notice when Harold got very masculine sideburns and stubble in an almost rugged way, but then it clicked to me why Maggie looks like a new character and yet so familiar, she is in essence the female form of Harold. I love it when designs still retain faithful facial features no matter what gender they are depicted in. The chemistry between the two male main leads is great and typical for an established romantic relationship where they already are comfortable with each other. I was actually surprised this is not some type of prequel or spin-off game because they already feel very realised with a rich history behind them.
I can totally see the potential of the imp system in this VN as it's fun and original and also gives it a gameplay hook, where you can't tell someone's hidden superpower from just meeting them first. The mystery itself is sound and works really well as what you describe as the first episode in a mystery series: the writing is tight where we are introduced to the heroes, they solve the mystery, and it ends on a funny note. (I'm also low-key glad that the mystery is entry-level so I won't be stressing out too much that I couldn't figure out who the culprit is, haha.)