Planetes Word Game

The Wife and I recently finished watching the anime series Planetes, which is about the crew of a space ship that cleans up debris in Earth orbit in the late 21st century.  At the end of the final episode, the romantic leads, Hachimaki and Ai, are spending one last EVA together for old time's sake before he (Hachimaki) goes off to complete his training for the first mission to Jupiter, a journey that will take seven years round-trip.  As they float together in their space suits, they exchange a peculiar dialog, each in turn saying a different, seemingly unrelated word to the other.  At first, I thought they might be playing a low Earth orbit version of "I Spy" because several of the words are space-related, but then I figured it out: they're playing shiritori.

Shiritori (尻取り, lit. 'taking the bottom') is a game in which players take turns saying words, each of which must begin with the kana character (mora) that ended the previous player's word.  For example, if one player says 花 (hana 'flower'), the next player could follow with 夏 (natsu 'summer'), because the former ends with na and the latter begins with it.  The game continues until a player either can't think of a word that hasn't already been played or accidentally says a word that ends with the final nasal ん, which cannot appear at the beginning of a Japanese word.

I've reproduced the dialog between Hachimaki and Ai below, with Hepburn romanizations and my (somewhat free) translations:

H:	ケ。ケッスラーシンドロム。 ke.  kessuraa shindoromu. "Ke".  Kessler Syndrome.
A:	ム。無重量用軸受け。 mu.  mujuuryouyou jikuuke. Zero gravity bearing.
H:	ケレス。 keresu. Ceres.
A:	ス？ス。スピン抜け。 su?  su.  supinnuke. Spin release.
H:	ケ。計器飛行。 ke.  keiki hikou. Instrument flight.
A:	ウインドウ開け。 uindou ake. Window opener.
H:	ケネディ宇宙センター。 kenedi uchuu sentaa. Kennedy Space Center.
A:	ア？アですか？ a?  a desuka? "A"?  Is it "a"?
H:	ア。 a. It's "a".
A:	アナンケ。 ananke. Ananke [a moon of Jupiter]
H:	ケ、ケ。鍵盤ハーモニカ。 ke, ke.  kenban haamonika. Keyboard harmonica.
A:	髪の毛。 kami no ke. Hair.
H:	又ケかよ？ mata ke ka yo?  [I think it's ka yo, though that sounds a little odd.] "Ke" again?
A:	もうないでしょう？ mou nai deshou? Can't you think of another?
H:	ケね。あるよ。結婚しよう。ウだよ。 ke ne.  aru yo.  kekkon shiyou.  u da yo. "Ke", huh.  Ah, got one.  Will you marry me?  That's "u" to you.
A:	うん。 un. Yes.
H:	[ヨシャ。]お前の負け。 [yo sha.]  Omae no make. [I can't make this out.]  You lose!

Some of these are a little tricky.  In particular, the Japanese spelling of Kennedy Space Center ends with the katakana long vowel symbol, so Ai needs to clarify that she's supposed to follow up with a word beginning with a.  There's another more clever trick being played throughout the game, though—do you see it?  Regardless of what word Hachimaki chooses, Ai keeps coming back with words that ends in ke.  Eventually he can't think of any more words, so Ai has to prod him a little bit—forgive him, he's male—until he finally takes the hint and asks her to marry him.  When he says kekkon shiyou 'Let's get married', he overpronounces it slightly—it would ordinarily end with a phonetic long [o], but he pronounces the u, leaving it up to Ai whether she will reply with the casual form un 'yes' or uun 'no'.  When she replies un, which ends with the final nasal, Hachimaki declares himself the winner of the game.  Presumably Ai is thinking, "You just keep telling yourself that, smart guy."

There's another interesting linguistic bit in the series that involves the radio jargon "You copy?" and "I copy!", which have been borrowed into the characters' futuristic space Japanese as aicopii and yuucopii.  What's surprising is how they make the polite forms.  Several times in the series, Ai (a trainee) is asked by Hachimaki (her instructor): yuucopii?  Instead of simply replying aicopii, which would be a plain form and inappropriately familiar, she replies aicopii desu, adding the polite version of the copula (lit. 'It's "I copy"').  I was a little surprised by this since there's a straightforward way in Japanese of making foreign-vocabulary nouns into verbs: the addition of the light verb suru 'do', which can then be marked for various levels of formality.  In this case, Ai could have used aicopii shimasu as the polite form, but instead she used aicopii desu.  Maybe there's a subtle difference in meaning between the two that I'm not fluent enough to detect.  Anybody know?