Simply put: this is filth. It is not the worst Light Novel ever written... except for the fact that it is. I'll keep it short and simple and cut straight to the chase, since this is my first non-positive review and I don't want it to turn into a long-winded rant.
The story is unoriginal; it has a lot of predictable plot points, and a really uninspiring storytelling. The swimming scenes are vastly entertaining, they felt vivid and were obviously the highlight of the story, there were many explanations and terminologies about swimming which were very informative and fun to read. Other than said scenes there were little to no good things to point out.

The cast was horrible, they were boring, bland, generic, unmemorable, depthless and they had little to no development, they were nothing but archetypes. Haruka, the dull stoic protagonist. Makoto, the bland "Team Mom". Rin and Sousuke, the tiresome rivals, the former is a tsundere crybaby and the latter is a downright prick. Nagisa, the bothersome hyperactive child. The supporting cast was just as bland with the exception of Aki, which was interesting and Kisumi which was easily the best character from the franchise, his playful personality and his cheerful antics were always entertaining but never annoying, definitely the 'best boy' from this novel.

The boring interactions between the underwhelming cast were a chore to go through and the melodramatic scenes were painful to read, to top it all off the dialogues were horrible, every line uttered was so unrealistic that made me ask myself 'did the person who wrote this ever talked/interacted with males in her entire life?'.

The art, much like the swimming scenes are also another good thing to point out, it was satisfactory, the backgrounds were detailed and had a great texture, there was a nice set of color with lots of vibrancy. The characters on the other hand all had generic character designs and looked way too similar to each other with the sole exceptions of hair colors and some height differences.

The main purpose of this novel is fanservice/pandering and nothing more. The (Project) K anime was underwhelming but it's other medias were very good to read and vastly superior to its animated counterparts and that inspired me to check on High Speed!, expecting the same to happen. All I have to say is that it didn't. Free!/High Speed! remains a franchise that is full of potential but never fully utilizes it and this novel is the weakest part of it. Lackluster story, generic and unremarkable characters, only some few redeemable points and not to mention a questionable choice of terms/words to use such as: rape blossoms, sperm whale and a dog named 'Dick', as well as many innuendos and Ho Yay overtones.

If you're a fan of this franchise, this novel was designated mainly for you, but if you're searching for a gripping story with memorable characters with depth, personality and development and also a great storytelling look somewhere else. And I also must say that with This novel, Chuu2 and Musaigen, KyoAni/K.A Esuma bunko truly hit the rockbottom, hopefully Violet Evergarden seems promising and may even change my opnion about this studio/label.

Pros:
+Swimming scenes are good/entertaining as well as some terminology/details about said sport;
+Good art(style);
+Kisumi;
+It ends.

Cons:
-Everything else.

Similar recommendations for those looking for stories centered around competition/friendship/youth/hardships but executed well with the addition of actual characters:
Seishun Kouryakuhon, Nijiiro Days, Tsuritama, Hibike! Euphonium, Chihayafuru, 3-gatsu no Lion, Nagi no Asukara, Sakamichi no Apollon, Mother's Rosario and Shigatsu wa Kimi no Uso.

... Last updated on June 29th, 2017, 10:28am