Tensei Shitara Ken Deshita

Story:

I opened my eyes and woke up in a secret valley, and monsters were swarming around me. When I looked around, I was shocked, but some time later I discovered that…I had become a sword! The most real magical weapon that absorbs magical stones and gains skills. How did this happen? All my life I have lived the life of an ordinary otaku, and now I have moved to a different reality and become a sword!