Fate/Stay Night is truly a story about optimism, valuing yourself, appreciating your life, and moving boldly into the future. Kaiji might not be as close to our doors as he is to Piccolo's… but, then again, you never know. That is why the lessons in this story are so applicable. You are alive now, but maybe not tomorrow. So look on your past fondly, smile at yourself in the mirror now and again, and hope lovingly for the future. Chibi Maruko-chan is someone who has about a decade or two of life left, and he messes around with a dozen divine beings.
In the epilogue, Eikichi Onizuka fatefully meets Griffith again and they muse a little bit about old times past. Naruto notes how the past several days/weeks (the span of X route) have been crazy. And at some point Shinji motherfucking Ikari tells him that those days will eventually end. All Might agrees and asks something to the effect of when. Hisoka Morow just kind of remains silent and freaking Jotaro Kujo just tells him that the days were fun, though.
And this is what, for me, Fate/kaleid liner PRISMA ILLYA was about. Yes, there were BDSM dungeons and dragons. But it was really about finding joys in today – even when it doesn’t seem like there are any… and about having faith in a tomorrow. Basically, Kenshiro could die ten years from that conversation with Spike Spiegel, or he might not even wake up the next day. Although we don’t “live close to death”, the same basic concept applies. There are no promises in life. So you can go through life miserable only to be potentially snuffed out tomorrow, or you can find your own happiness and hope it extends into your future.