I wanted to know if every ending is bad or is the result of dying, is there a good end? Or is the good ending just not dying and continuing to spend time with Jun? Also can I continue on the same save file after an ending

Under one comment in which one person asked for a good or neutral ending to be added, the author said that they would add it. (He didn't specify when this would be)

目前只有坏结局，作者在某个帖子中说明了以后会添加好结局

Currently, yes. The happy end is playing forever in the current update.