Because this is chance encounter with 〜ので
Grammar Explanation: Objective reason with 〜ので

When Cocoa picks up another student’s dropped handkerchief, she uses the opportunity to show off her devilish nature to Chiya they discussed earlier.
- ココア:
- 「これも何かの縁
( なので今度( お昼( 一緒( にどうですか?」- “How about we have lunch together next time, since this, too, is a meeting of chance?”
See Also
- Kanji: Measures and degrees with 度
- Kanji: Now and the present with 今