.kv doesn't support unicode

main.py

from kivy.app import App

from kivy.uix.label import Label
from kivy.uix.boxlayout import BoxLayout

class ScatterTextWidget(BoxLayout):
    txt = "愛　あい"

class TestWidget(App):
    def build(self):
        return ScatterTextWidget()


if __name__ == "__main__":
    TestWidget().run()

TestWidget.kv

<ScatterTextWidget>:
    Label:
        text: root.txt
        font_name: 'TakaoPMincho.ttf'
        font_size: sp(48)