If Tetsu willing to convert his religion for the sake of Syikin, you need to love Islam very deep. I mean, blend yourself the religion 1st (as its the only way). Makes yourself love Islam in front of her, but be honest to love Islam and don't pretend to love it. Examples are as follows:-

-Each time you wanna say hi to Syikin when meet each other, say "Assalamualaikum" instead of "hi".
- If she say hi to you, answered it with "Wa'alaikumussalam"
- Ask some question regarding Islam frequently from her to show that you interested/curious to know about Islam. Such as "Kenapa orang Islam tak makan daging babi ah?","Kenapa orang Islam suka malan buah kurma?", "Kenapa saya nampak sesetengah perempuan Islam (or Muslimah) tidak berpuasa tapi takder orang kecoh pun?", "Kenapa setiap kali orang Islam sembahyang, dia kena cuci muka, kaki dan tangan dulu?", or any question that you curious about Islam.
-Get to know her muslim life. Example like now, fasting month already dekat. You can learn puasa with her. Join her puasa also. Show yourself that you willing to go through the fasting month with her. When near 'buka puasa', ask her to 'buka puasa' with you at nearby malay restaurant.

But of course, you need to know her feeling that she's willing to accept you if you willing to accept Allah more than her.

But it takes time for her to accept you. You need to be patience.

This is my advise if Tetsu willing to convert. If not, forget my advise above.