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Minor example; Momotarou's drop in performance during the Samezuka training sessions in episode 4 actually quite nicely illustrates his favorite proverb - "even Homer nods". "To nod" here actually does not mean the motion you do to say yes, but actually the one when you fall asleep, that is "nod off". The proverb means that even a genius (or an excellent athlete such as Momotarou) sometimes turns in inferior work compared to what they usually deliver.
If we take them separately, Makoto and Rin's backstories are already pretty traumatizing for a small child. Now if we look at them together we see that they have quite a lot in common: Both lost someone they cared about, Rin his father and Makoto the old man he was friends with, in a typhoon that sank their boat three kilometers off the coast. In episode 6 we see Makoto clinging to Haruka as a funeral part walks by and in episode 7 Rin is seen with Gou being part of one. Coincidence? I think not.