Seishin-Kan in Chinese / Japanese...

聖心館 is the martial arts style Seishin-Kan or Seishinkan in Japanese Kanji.

The meaning is “Sacred Heart Hall” or “House of the Sacred/Good Heart”.

Do not confuse Seishin-Kan with Seishi-Kan! It's not the same!

精神武道 is the Japanese martial arts title, Seishin Budo.

The first two characters, 精神, can mean vigor, vitality, drive, spiritual, mind, spirit, soul, heart, ethos, attitude, mentality, will, intention, essence, and fundamental significance.

The last two characters, 武道, are the Japanese word for martial arts (literally the Martial Way). This title can also be romanized as Seshin Budou or Seishin Budō.

精神武道館 is the title Seishin Budokan in Japanese Kanji.

押忍の精神 is the name Osu No Seishin or “Spirit of Osu” in Japanese.

This Spirit of Osu is an essential concept in Karate. You will hear “Osu!” shouted in every Karate dojo which is not just a sign of respect and obedience to the Sensei but also means patience, determination, and perseverance. Shouting “Osu!” serves as a reminder to embody these qualities.

聖心会 is the Japanese martial arts title “Seishinkai” or “Seishin-Kai.”

It literally means “Sacred Heart Association” or “Pure-Heart Club.”

聖 can mean holy, sacred, saint, sage, virtuous, expert, wise and good, upright, or correct.
心 can mean heart, mind, center, core, spirit, soul, or vitality.

聖心 creates a word meaning sacred heart, or the holy mind (that of Buddha).
会 in Japanese means association, club, meeting, assembly, party, gathering, conference, athletic meet, or society.

不屈の精神 is one of several versions or ways to write “Indomitable Spirit” in Japanese.

This one is the famous “Fukutsu no Seishin” phrase.

精神 is the kind of spirit you have if you perform well in sports or competitions. It is the idea of having a good attitude and putting your all into something - so much so that others can see or feel your spirit. It is the essence of your being that can only be subjectively described because there are no words that can fully explain what “spirit” really is.

For your information:
My Japanese dictionary further tries to explain this word by comparing it to mind, soul, heart, or intention.
My Chinese dictionary compares these characters to meanings like vigor, vitality, drive, and mentality.
My Korean dictionary defines this as mind, spirit, and soul.

See Also:  Vitality | Heart | Soul