  With an aim to shed light on the origin of Li anomaly observed in a small
fraction of red giants, we carried out a spectroscopic study on the
observational characteristics of selected 20 bright Li-rich giants, in
comparison with a large number of normal late G-early K giants, where special
attention was paid to clarifying any difference between two samples with
respect to stellar parameters, rotation, activity, kinematic properties, and
chemical abundances of Li, Be, C, O, Na, S, and Zn). Our targets are roughly
divided into 'bump/clump group' and 'luminous group' according to the position
on the HR diagram. Regarding the former group, Li-enriched giants and the
corresponding normal giants appear practically similar except for Li,
suggesting that surface Li enhancement in this group may be a transient episode
which normal giants undergo at some certain evolutionary stage. Meanwhile,
those Li-rich giants belonging to the latter group appear more anomalous in the
sense that they tend to show larger rotational velocities, and that their
elemental abundances (e.g., those of C and O derived from high-excitation
lines) are apt to show apparent overabundances, though this might be due to
some spurious effect reflecting the difficulty of abundance derivation in stars
of higher rotation and activity. Our analysis confirmed considerable Be
deficiency as well as absence of 6Li as the general characteristics of Li-rich
giants under study, which implies that engulfment of planets is rather unlikely
for the cause of Li-enrichment.
