Yesteryear’s Lanterns and the Guhua of Today is a Lantern Rite Tale in Genshin Impact. It becomes available during the second stage of the Lantern Rite event and will be available in the Huagunag Stone Forest.
Travel to the Huaguang Stone Forest and speak with Sun Yu. He will want to make a Xiao Lantern but will need a Qingxin Flower to do it. This is not the usual method and is something that only his clan does.
Where to find Qingxin Flowers
You can find Qingxin Flowers at the tops of cliffs in Liyue. It can be found all around the Huaguang Stone Forest, so you will not need to travel far to find it. If you have Qiqi, you can add her to your party and she will mark all nearby Liyue resources on your map, making them even easier to find.
Return to Sun Yu and give him the plant, after talking with him again he will ask you to go to the Mt. Tianheng and release the lantern. Whilst there, you will meet a character called Zhiruo.
Zhiruo is a former member of Sun Yu’s clan, and you will need to walk with her as she recounts some stories from her past. When she has finished, return once again to Sun Yu. Tell him what happened, and this will complete the mission. You will receive 30 Primogems, 20000 Mora, and 100 Festive Fever.