It is heavily implied Master Panda is actually Shiki Nanaya (from speaking with the same voice in Carnival Phantasm, the symbol for "Nanatsu-yoru" on his back, Shiki Nanaya and Miyako's tagteam name in Act Cadenza is "The Long Road of the Panda," etc.)
He taught martial arts to Miyako Arima and entertains kids in the park.
Miyako highly respects him.
He later makes an appearance in Carnival Phantasm, often appearing to give Miyako advice. He also appears as one of the characters sitting in the background. He appears unmasked at the time but is too small to be identified.
Melty Blood: Type Lumina
Master Panda appears in Miyako's Last Arc Final Thunder - Smashing Fist (ぜつぎらいきょくあんぽんけん?), performing a series of attacks with her. He also appears in Powered Ciel's Last Arc when used on Miyako, taking the blow for Miyako.
Master Panda is a master practitioner of Bajiquan.
In Miyako's Last Arc in Type Lumina, Final Thunder - Smashing Fist (ぜつぎらいきょくあんぽんけん?), Master Panda performs a series of attacks strikingly similarly to many of Shiki Nanaya'a moves, like Flash Sheath - Eightfold Thrust and Crescent Moon Nanaya.
 Character Material - SISTER&CHINESE HONEY: Cap Girl, p.047
Class: First-year, class B.
Affiliated to: Super Aikido Club, Unexplored Cuisine Research Society
Likes: Club activities, Old Kung-fu movies
Dislikes: Discussing about love, seniors.
Favorite foods: Chinese dumplings, Bright-red Mapo that she ate someday, somewhere
Dislikes: Supplements, Bright-red Sandwich that she ate someday, somewhere
Hobbies: Baseball, Soccer, Kung-fu
Aspirations: Open a shop of delicious chinese food
Respected/worthy people for her: Master Panda
Blood type: O
Birthday: May 4.
Source: Spinning Type-Moon